config: Add CONFIG_NFS_SWAP

See: https://github.com/raspberrypi/firmware/issues/266
diff --git a/arch/arm/configs/bcmrpi_defconfig b/arch/arm/configs/bcmrpi_defconfig
index 9810e9d..e480e7e 100644
--- a/arch/arm/configs/bcmrpi_defconfig
+++ b/arch/arm/configs/bcmrpi_defconfig
@@ -1018,6 +1018,7 @@
 CONFIG_NFS_FS=y
 CONFIG_NFS_V3_ACL=y
 CONFIG_NFS_V4=y
+CONFIG_NFS_SWAP=y
 CONFIG_ROOT_NFS=y
 CONFIG_NFS_FSCACHE=y
 CONFIG_NFSD=m