qapi: make visit_type_size fallback to type_int

Currently visit_type_size checks if the visitor's type_size function pointer is
NULL. If not, it calls it, otherwise it calls v->type_uint64(). But neither of
these pointers are ever set. Fallback to calling v->type_int() in this third
(default) case.

Signed-off-by: Vasilis Liaskovitis <vasilis.liaskovitis@profitbricks.com>
Add SIZE type to qdev properties

This patch adds a 'SIZE' type property to qdev.

It will make dimm description more convenient by allowing sizes to be specified
with K,M,G,T prefixes instead of number of bytes e.g.:
-device dimm,id=mem0,size=2G,bus=membus.0

Credits go to Ian Molton for original patch. See:
http://patchwork.ozlabs.org/patch/38835/

Signed-off-by: Vasilis Liaskovitis <vasilis.liaskovitis@profitbricks.com>
qemu-option: export parse_option_number

Signed-off-by: Vasilis Liaskovitis <vasilis.liaskovitis@profitbricks.com>
Implement dimm device abstraction

Each hotplug-able memory slot is a DimmDevice. All DimmDevices are attached
to a new bus called DimmBus. This bus is introduced so that we no longer
depend on hotplug-capability of main system bus (the main bus does not allow
hotplugging). The DimmBus should be attached to a chipset Device (i440fx in case
of the pc)

A hot-add operation for a particular dimm:
- creates a new DimmDevice and attaches it to the DimmBus
- creates a new MemoryRegion of the given physical address offset, size and
node proximity, and attaches it to main system memory as a sub_region.

Hotplug operations are done through normal device_add commands.
Also add properties to DimmDevice.

v3->v4: Removed hot-remove functions. Will be offered in separate patches.
vl: handle "-device dimm"

Signed-off-by: Vasilis Liaskovitis <vasilis.liaskovitis@profitbricks.com>
acpi_piix4 : Implement memory device hotplug registers

A 32-byte register is used to present up to 256 hotplug-able memory devices
to BIOS and OSPM. Hot-add and hot-remove functions trigger an ACPI hotplug
event through these. Only reads are allowed from these registers.

An ACPI hot-remove event but needs to wait for OSPM to eject the device.
We use a single-byte register to know when OSPM has called the _EJ function
for a particular dimm. A write to this byte will depopulate the respective dimm.
Only writes are allowed to this byte.

v1->v2:
mems_sts address moved from 0xaf20 to 0xaf80 (to accomodate more space for
cpu-hotplugging in the future).
_EJ array is reduced to a single byte.
Add documentation in docs/specs/acpi_hotplug.txt

v3->v4: Removed hot-remove functions, will be added separately. Updated for
memory API.

Signed-off-by: Vasilis Liaskovitis <vasilis.liaskovitis@profitbricks.com>
acpi_ich9 : Implement memory device hotplug registers

This implements acpi dimm hot-add capability for q35 (ich9). The logic is the
same as for the pc machine (piix4).

TODO: Fix acpi irq delivery bug. Currently there is a flood of irqs when
delivering an acpi interrupt (should be just one). Guest complains as follows:
"irq 9: nobody cared
[...]
Disabling IRQ #9"

where #9 is the acpi irq