common: Move command functions out of common.h

Move these functions into the command.h header file which is a better fit.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/board/inversepath/usbarmory/usbarmory.c b/board/inversepath/usbarmory/usbarmory.c
index de4ad83..1951018 100644
--- a/board/inversepath/usbarmory/usbarmory.c
+++ b/board/inversepath/usbarmory/usbarmory.c
@@ -8,6 +8,7 @@
  */
 
 #include <common.h>
+#include <command.h>
 #include <asm/io.h>
 #include <asm/arch/imx-regs.h>
 #include <asm/arch/sys_proto.h>