blk_mq: linux/blk-mq.h does not include all the headers it depends on

and building block/blk-mq-pci.o should depend on CONFIG_BLOCK

Fixes: 973c4e372c ("blk-mq: provide a default queue mapping for PCI device")
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

block/Kconfig

@@ -124,4 +124,9 @@ config BLOCK_COMPAT
 	depends on BLOCK && COMPAT
 	default y
 
+config BLK_MQ_PCI
+	bool
+	depends on BLOCK && PCI
+	default y
+
 source block/Kconfig.iosched

block/Makefile

@@ -22,4 +22,4 @@ obj-$(CONFIG_IOSCHED_CFQ)	+= cfq-iosched.o
 obj-$(CONFIG_BLOCK_COMPAT)	+= compat_ioctl.o
 obj-$(CONFIG_BLK_CMDLINE_PARSER)	+= cmdline-parser.o
 obj-$(CONFIG_BLK_DEV_INTEGRITY) += bio-integrity.o blk-integrity.o t10-pi.o
-obj-$(CONFIG_PCI)		+= blk-mq-pci.o
+obj-$(CONFIG_BLK_MQ_PCI)	+= blk-mq-pci.o

block/blk-mq-pci.c

@@ -10,6 +10,8 @@
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  * more details.
  */
+#include <linux/kobject.h>
+#include <linux/blkdev.h>
 #include <linux/blk-mq.h>
 #include <linux/blk-mq-pci.h>
 #include <linux/pci.h>