L4Linux: fix usage of l4_touch_xx (fix #682)

Use size in bytes, when touching memory via l4_touch_ro or l4_touch_rw, instead
of log2 size.
base-foc: remove links to obsolete initrd archives

Fix #686
Remove 'epit' from generic i.MX platform spec

Remove the 'epit' variable from the generic imx31 and imx53 specification,
and only add it to base-hw specific i.MX specs. Thereby the EPIT timer
library gets build for base-hw only.
Moreover, fix some const-ness issues in the platform_timer implementation
for the EPIT timer.
Fixes #688.
foc: Select "thread-ready" bit in pause function
foc: Extend irq mode heuristics

Explicitly set default mode for legacy interrupts to not rely on kernel
default settings. This patch fixes the constantly busy IRQ threads for
IRQ 1 and 12 as soon as the PS/2 driver was loaded until the point when
the first IRQ occurred.
usb: Rewrote back-end allocators

Allocate back-end memory dynamically.
base-foc: Do not touch memory during map operation

Don't do anything in Mapping::prepare_map_operation.  At this point and in the
current implementation, the memory has been mapped and cleared already. Touching
the memory may only pollute the cache causing data corruption in DMA memory.

Fixes issue #452
dde_linux: add network support for arndale board
dde_linux: use usleep for udelay
dde_linux: check for valid virt->phys translation
dde_linux: grab urb sizes from driver

Instead of hardcoding the values, ask the driver for the supported sizes and
allocate the skb allocators accordingly.