nfs: fix pnfs Kconfig defaults

Defaulting to m seem to prevent building the pnfs layout modules into the
kernel.  Default to the value of CONFIG_NFS_V4 make sure they are
built in for built-in NFSv4 support and modular for a modular NFSv4.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/Kconfig

@@ -116,17 +116,17 @@ config NFS_V4_2
 config PNFS_FILE_LAYOUT
 	tristate
 	depends on NFS_V4_1
-	default m
+	default NFS_V4
 
 config PNFS_BLOCK
 	tristate
 	depends on NFS_V4_1 && BLK_DEV_DM
-	default m
+	default NFS_V4
 
 config PNFS_OBJLAYOUT
 	tristate
 	depends on NFS_V4_1 && SCSI_OSD_ULD
-	default m
+	default NFS_V4
 
 config NFS_V4_1_IMPLEMENTATION_ID_DOMAIN
 	string "NFSv4.1 Implementation ID Domain"