intel/fsp: Fix microcode including

IS_ENABLED() requires the full define (incl. CONFIG_ prefix)
but isn't needed here.

Change-Id: I91d504367c75ce3fcecc6fa2499afaa0896595d3
Signed-off-by: Patrick Georgi <patrick@georgi-clan.de>
Reviewed-on: http://review.coreboot.org/4646
Tested-by: build bot (Jenkins)
Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
1 file changed