MAINTAINERS: add missing block layer user API header files

Add the missing user API header files related to the block layer to the
list of matching file patterns for Jens's block layer entry.

Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: damien-lemoal

MAINTAINERS

@@ -4400,6 +4400,8 @@ F:	block/
 F:	drivers/block/
 F:	include/linux/bio.h
 F:	include/linux/blk*
+F:	include/uapi/linux/blk*
+F:	include/uapi/linux/ioprio.h
 F:	kernel/trace/blktrace.c
 F:	lib/sbitmap.c