fs: Allow to compile CMD_UBIFS when SPL is enabled

Currently there is no UBIFS support in SPL. But macro CONFIG_CMD_UBIFS is
defined also when building SPL. when both CMD_UBIFS and SPL are enabled
then build process throw compile error.

Fix check for ubifs code in fstypes[] to allow compiling CMD_UBIFS only in
proper U-Boot.

Signed-off-by: Pali Rohár <pali@kernel.org>

fs/fs.c

@@ -267,6 +267,7 @@ static struct fstype_info fstypes[] = {
 		.ln = fs_ln_unsupported,
 	},
 #endif
+#ifndef CONFIG_SPL_BUILD
 #ifdef CONFIG_CMD_UBIFS
 	{
 		.fstype = FS_TYPE_UBIFS,
@@ -286,6 +287,7 @@ static struct fstype_info fstypes[] = {
 		.ln = fs_ln_unsupported,
 	},
 #endif
+#endif
 #ifdef CONFIG_FS_BTRFS
 	{
 		.fstype = FS_TYPE_BTRFS,