arch/x86: Always compile postcar library in romstage

postcar_loader.c has a useful library of funtions for
setting up stack and MTRRs. Make it available in romstage
irrespective of CONFIG_POSTCAR_STAGE for use in stack setup
after Dram init.

The final step of moving the used and max MTRRs on to stack
is moved to a new function, that can be used outside of
postcar phase.

Change-Id: I322b12577d74268d03fe42a9744648763693cddd
Signed-off-by: Rizwan Qureshi <rizwan.qureshi@intel.com>
Reviewed-on: https://review.coreboot.org/16331
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
3 files changed