lightnvm: include NVM Express driver if OCSSD is selected for build

Because NVM needs BLK_DEV_NVME, select it automatically if we mark NVM
in config file before building kernel.  Also append PCI to depends as
select doesn't automatically add dependencies.

Signed-off-by: Rakesh Pandit <rakesh@tuxera.com>
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/lightnvm/Kconfig

@@ -4,7 +4,8 @@
 
 menuconfig NVM
 	bool "Open-Channel SSD target support"
-	depends on BLOCK && HAS_DMA
+	depends on BLOCK && HAS_DMA && PCI
+	select BLK_DEV_NVME
 	help
 	  Say Y here to get to enable Open-channel SSDs.