MAINTAINERS: add coverage for drivers/block

To help folks like me that use scripts/get_maintainer.pl.

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/MAINTAINERS b/MAINTAINERS
index 93a12af..24f36c4 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2683,6 +2683,7 @@
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git
 S:	Maintained
 F:	block/
+F:	drivers/block/
 F:	kernel/trace/blktrace.c
 F:	lib/sbitmap.c