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>