cpu/amd/agesa/family15tn: Add initial support for SMM mode

This is the minimal setup needed to be able to execute SMI handlers.
Only support for ASEG handlers is added, which should be sufficient
for Trinity (up to 4 cores).

There are a few hacks which need to be introduced in generic code in
order to make this work properly, but these hacks are self-contained.
They are a not a result of any special needs of this CPU, but rather
from a poorly designed infrastructure. Comments are added to explain
how such code could be refactored in the future.

Change-Id: Iefd4ae17cf0206cae8848cadba3a12cbe3b2f8b6
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-on: http://review.coreboot.org/5493
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@gmail.com>
cpu/amd/agesa/family15tn: Add udelay implementation for SMM

This is a small implementation which uses only MSRs and rdtsc, without
relying on northbridge or other system hardware. It's SMM safe in that
it only reads registers, and doesn't modify the state of the hardware.

Change-Id: Ifa02ca73455b382f830c9b30b80b4f1bb18706b4
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-on: http://review.coreboot.org/5501
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@gmail.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>