amd: Don't call halt() when in SMM

This copies what Intel does.

BUG=b:80295434
TEST=grunt: Made sure that the S5 SMI interrupt gets fired.

Change-Id: I7874824cad01054c6bdeff12d248e671f27be030
Signed-off-by: Raul E Rangel <rrangel@chromium.org>
Reviewed-on: https://review.coreboot.org/26545
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
1 file changed