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/net/fastboot.c b/net/fastboot.c
index 8afc552..0c57fb9 100644
--- a/net/fastboot.c
+++ b/net/fastboot.c
@@ -4,6 +4,7 @@
  */
 
 #include <common.h>
+#include <command.h>
 #include <fastboot.h>
 #include <net.h>
 #include <net/fastboot.h>