fs: separate CONFIG_FS_{FAT, EXT4} from CONFIG_CMD_{FAT, EXT*}

This makes the FAT and ext4 filesystem implementations build if
CONFIG_FS_{FAT,EXT4} are defined, rather than basing the build on
whether CONFIG_CMD_{FAT,EXT*} are defined. This will allow the
filesystems to be built separately from the filesystem-specific commands
that use them. This paves the way for the creation of filesystem-generic
commands that used the filesystems, without requiring the filesystem-
specific commands.

Minor documentation changes are made for this change.

The new config options are automatically selected by the old config
options to retain backwards-compatibility.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Benoît Thébaudeau <benoit.thebaudeau@advansee.com>
diff --git a/fs/ext4/Makefile b/fs/ext4/Makefile
index 82cd9ae..bb801f9 100644
--- a/fs/ext4/Makefile
+++ b/fs/ext4/Makefile
@@ -30,11 +30,8 @@
 LIB	= $(obj)libext4fs.o
 
 AOBJS	=
-COBJS-$(CONFIG_CMD_EXT4) := ext4fs.o ext4_common.o dev.o
-ifndef CONFIG_CMD_EXT4
-COBJS-$(CONFIG_CMD_EXT2) := ext4fs.o ext4_common.o dev.o
-endif
-COBJS-$(CONFIG_CMD_EXT4_WRITE) += ext4_journal.o crc16.o
+COBJS-$(CONFIG_FS_EXT4) := ext4fs.o ext4_common.o dev.o
+COBJS-$(CONFIG_EXT4_WRITE) += ext4_journal.o crc16.o
 
 SRCS	:= $(AOBJS:.o=.S) $(COBJS-y:.o=.c)
 OBJS	:= $(addprefix $(obj),$(AOBJS) $(COBJS-y))
diff --git a/fs/ext4/ext4_common.c b/fs/ext4/ext4_common.c
index d6d55b9..323875f 100644
--- a/fs/ext4/ext4_common.c
+++ b/fs/ext4/ext4_common.c
@@ -56,7 +56,7 @@
 struct ext2_inode *g_parent_inode;
 static int symlinknest;
 
-#if defined(CONFIG_CMD_EXT4_WRITE)
+#if defined(CONFIG_EXT4_WRITE)
 uint32_t ext4fs_div_roundup(uint32_t size, uint32_t n)
 {
 	uint32_t res = size / n;
diff --git a/fs/ext4/ext4_common.h b/fs/ext4/ext4_common.h
index f728134..87cab16 100644
--- a/fs/ext4/ext4_common.h
+++ b/fs/ext4/ext4_common.h
@@ -37,7 +37,7 @@
 #include <ext4fs.h>
 #include <malloc.h>
 #include <asm/errno.h>
-#if defined(CONFIG_CMD_EXT4_WRITE)
+#if defined(CONFIG_EXT4_WRITE)
 #include "ext4_journal.h"
 #include "crc16.h"
 #endif
@@ -71,7 +71,7 @@
 int ext4fs_iterate_dir(struct ext2fs_node *dir, char *name,
 			struct ext2fs_node **fnode, int *ftype);
 
-#if defined(CONFIG_CMD_EXT4_WRITE)
+#if defined(CONFIG_EXT4_WRITE)
 uint32_t ext4fs_div_roundup(uint32_t size, uint32_t n);
 int ext4fs_checksum_update(unsigned int i);
 int ext4fs_get_parent_inode_num(const char *dirname, char *dname, int flags);
diff --git a/fs/ext4/ext4fs.c b/fs/ext4/ext4fs.c
index 3a5ef20..06536ba 100644
--- a/fs/ext4/ext4fs.c
+++ b/fs/ext4/ext4fs.c
@@ -196,7 +196,7 @@
 	return ext4fs_read_file(ext4fs_file, 0, len, buf);
 }
 
-#if defined(CONFIG_CMD_EXT4_WRITE)
+#if defined(CONFIG_EXT4_WRITE)
 static void ext4fs_update(void)
 {
 	short i;