fs: implement size/fatsize/ext4size

These commands may be used to determine the size of a file without
actually reading the whole file content into memory. This may be used
to determine if the file will fit into the memory buffer that will
contain it. In particular, the DFU code will use it for this purpose
in the next commit.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
diff --git a/common/cmd_fs.c b/common/cmd_fs.c
index 78590d2..6754340 100644
--- a/common/cmd_fs.c
+++ b/common/cmd_fs.c
@@ -20,6 +20,19 @@
 #include <command.h>
 #include <fs.h>
 
+static int do_size_wrapper(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
+{
+	return do_size(cmdtp, flag, argc, argv, FS_TYPE_ANY);
+}
+
+U_BOOT_CMD(
+	size,	4,	0,	do_size_wrapper,
+	"determine a file's size",
+	"<interface> <dev[:part]> <filename>\n"
+	"    - Find file 'filename' from 'dev' on 'interface'\n"
+	"      and determine its size."
+);
+
 static int do_load_wrapper(cmd_tbl_t *cmdtp, int flag, int argc,
 				char * const argv[])
 {