MAINTAINERS: update SFI pattern

commit 937f961a ("x86: Move sfi to platform") moved the files, update
the pattern.
Signed-off-by: Joe Perches <joe@perches.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

MAINTAINERS

@@ -5657,7 +5657,7 @@ L:	sfi-devel@simplefirmware.org
 W:	http://simplefirmware.org/
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-sfi-2.6.git
 S:	Supported
-F:	arch/x86/kernel/*sfi*
+F:	arch/x86/platform/sfi/
 F:	drivers/sfi/
 F:	include/linux/sfi*.h