nb/i945/gma.c: use IS_ENABLED instead of #if, #endif

Change-Id: Ib58126e1c9001ed679e161d6d06241fac762bdb3
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/17049
Tested-by: build bot (Jenkins)
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
1 file changed