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/arch/powerpc/lib/kgdb.c b/arch/powerpc/lib/kgdb.c
index f580c02..4a3e26c 100644
--- a/arch/powerpc/lib/kgdb.c
+++ b/arch/powerpc/lib/kgdb.c
@@ -252,7 +252,7 @@
    the debugger. */
 
 void
-kgdb_breakpoint(int argc, char * const argv[])
+kgdb_breakpoint(int argc, char *const argv[])
 {
 	asm("	.globl breakinst\n\
 	     breakinst: .long 0x7d821008\n\