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/examples/api/demo.c b/examples/api/demo.c
index e752378..d586174 100644
--- a/examples/api/demo.c
+++ b/examples/api/demo.c
@@ -24,7 +24,7 @@
 
 static char buf[BUF_SZ];
 
-int main(int argc, char * const argv[])
+int main(int argc, char *const argv[])
 {
 	int rv = 0, h, i, j, devs_no;
 	struct api_signature *sig = NULL;