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/toradex/verdin-imx8mm/spl.c b/board/toradex/verdin-imx8mm/spl.c
index 338952e..eedca1e 100644
--- a/board/toradex/verdin-imx8mm/spl.c
+++ b/board/toradex/verdin-imx8mm/spl.c
@@ -4,6 +4,7 @@
  */
 
 #include <common.h>
+#include <command.h>
 #include <image.h>
 #include <init.h>
 #include <asm/arch/clock.h>