lightnvm: select CONFIG_CRC32

Without CRC32 support, this fails to link:

arm-linux-gnueabi-ld: drivers/lightnvm/pblk-init.o: in function `pblk_init':
pblk-init.c:(.text+0x2654): undefined reference to `crc32_le'
arm-linux-gnueabi-ld: drivers/lightnvm/pblk-init.o: in function `pblk_exit':
pblk-init.c:(.text+0x2a7c): undefined reference to `crc32_le'

Fixes: a4bd217b ("lightnvm: physical block device (pblk) target")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/lightnvm/Kconfig

@@ -19,6 +19,7 @@ if NVM
 
 config NVM_PBLK
 	tristate "Physical Block Device Open-Channel SSD target"
+	select CRC32
 	help
 	  Allows an open-channel SSD to be exposed as a block device to the
 	  host. The target assumes the device exposes raw flash and must be