ARM: exynos_defconfig: Enable NFSv4 client

NFS client is already enabled (NFS_FS) and by default it enables clients
for version 2 and 3. Enable explicitly the version 4 client to utilize
the newer protocol.

The NFS client is especially useful for testing kernel in automated
environments (network boot with network file system).
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com>

arch/arm/configs/exynos_defconfig

@@ -224,6 +224,7 @@ CONFIG_TMPFS_POSIX_ACL=y
 CONFIG_CRAMFS=y
 CONFIG_ROMFS_FS=y
 CONFIG_NFS_FS=y
+CONFIG_NFS_V4=y
 CONFIG_ROOT_NFS=y
 CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_ASCII=y