amd/agesa/f15tn: Invalid inline asm in gcc-intrin.h

Forward port commit:
db0e0e2 amd/agesa/*/gcc-intrin.h: Invaild inline asm

Change-Id: I87bf101b15bac7c06afa9cec10e2bd4e0cdfd6c7
Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>