NFSv4.1: make deviceid cache global

Move deviceid cache from the pnfs files layout driver to the
generic layer in preparation for the objects layout driver.

Signed-off-by: Benny Halevy <bhalevy@panasas.com>
diff --git a/fs/nfs/Makefile b/fs/nfs/Makefile
index 4776ff9..7516a8a 100644
--- a/fs/nfs/Makefile
+++ b/fs/nfs/Makefile
@@ -15,7 +15,7 @@
 			   delegation.o idmap.o \
 			   callback.o callback_xdr.o callback_proc.o \
 			   nfs4namespace.o
-nfs-$(CONFIG_NFS_V4_1)	+= pnfs.o
+nfs-$(CONFIG_NFS_V4_1)	+= pnfs.o pnfs_dev.o
 nfs-$(CONFIG_SYSCTL) += sysctl.o
 nfs-$(CONFIG_NFS_FSCACHE) += fscache.o fscache-index.o