Enable vt. This brings VGA-based console and terminal support to
ia64 for the very first time. Only 9 years in the making...

Note that the vt/vga driver does not actually make sure there's
VGA hardware at the standard/legacy VGA I/O port and memory I/O
addresses. This can cause machine checks if the H/W does not have
a VGA controller.
Further rework netinet6 address handling code:
* Set ia address/mask values BEFORE attaching to address lists.
Inet6 address assignment is not atomic, so the simplest way to
do this atomically is to fill in ia before attach.
* Validate irfa->ia_addr field before use (we permit ANY sockaddr in old code).
* Do some renamings:
  in6_ifinit -> in6_notify_ifa (interaction with other subsystems is here)
  in6_setup_ifa -> in6_broadcast_ifa (LLE/Multicast/DaD code)
  in6_ifaddloop -> nd6_add_ifa_lle
  in6_ifremloop -> nd6_rem_ifa_lle
* Split working with LLE and route announce code for last two.
Add temporary in6_newaddrmsg() function to mimic current rtsock behaviour.
* Call device SIOCSIFADDR handler IFF we're adding first address.
In IPv4 we have to call it on every address change since ARP record
is installed by arp_ifinit() which is called by given handler.
IPv6 stack, on the opposite is responsible to call nd6_add_ifa_lle() so
there is no reason to call SIOCSIFADDR often.
Removed unneeded and dangerous assignment.  It would probably cause NULL
refererence panic if compiler not optimize it out.

Found with:	Clang static analyzer
MFC after:	2 weeks
Add standard memory controller helper functions.
Generalize AT91 NAND support a bit. Be more flexible about ALE and CLE
address line assignment. Provide convenince function to set these things.
Connect NAND for the SAM9260EK eval board, as well as the HotE HL-201.
# expect more refinement as do more boards.
Add nand device and NANDFS into the mix for those boards that have
support for it at the moment.
Add VT kernel configuration to ease testing of vt(9), aka Newcons
Introduce grab and ungrab upcalls. When the kernel desires to grab the
console, it calls the grab functions. These functions should turn off
the RX interrupts, and any others that interfere. This makes mountroot
prompt work again. If there's more generalized need other than
prompting, many of these routines should be expanded to do those new
things.

Reviewed by:	bde (with reservations)
Introduce grab and ungrab upcalls. When the kernel desires to grab the
console, it calls the grab functions. These functions should turn off
the RX interrupts, and any others that interfere. This makes mountroot
prompt work again. If there's more generalized need other than
prompting, many of these routines should be expanded to do those new
things.

Should have been part of r260889, but waasn't due to command line typo.

Reviewed by:	bde (with reservations)
Free the dma memory from the dma map before destroying the dma map.
Optimize f_expand_number(), improving performance.

MFC After:	3 days