MAINTAINERS: add SPI co-maintainer.

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
diff --git a/MAINTAINERS b/MAINTAINERS
index a1a2ace..2b697cb 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4937,6 +4937,7 @@
 
 SPI SUBSYSTEM
 M:	David Brownell <dbrownell@users.sourceforge.net>
+M:	Grant Likely <grant.likely@secretlab.ca>
 L:	spi-devel-general@lists.sourceforge.net
 S:	Maintained
 F:	Documentation/spi/