command: Remove the cmd_tbl_t typedef

We should not use typedefs in U-Boot. They cannot be used as forward
declarations which means that header files must include the full header to
access them.

Drop the typedef and rename the struct to remove the _s suffix which is
now not useful.

This requires quite a few header-file additions.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/board/LaCie/net2big_v2/net2big_v2.c b/board/LaCie/net2big_v2/net2big_v2.c
index 8b97e1a..dbd8b57 100644
--- a/board/LaCie/net2big_v2/net2big_v2.c
+++ b/board/LaCie/net2big_v2/net2big_v2.c
@@ -246,7 +246,8 @@
 #if defined(CONFIG_KIRKWOOD_GPIO)
 /* Return GPIO push button status */
 static int
-do_read_push_button(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
+do_read_push_button(struct cmd_tbl *cmdtp, int flag, int argc,
+		    char *const argv[])
 {
 	return !kw_gpio_get_value(NET2BIG_V2_GPIO_PUSH_BUTTON);
 }