Since

|commit d22b85a
|Author: Sascha Hauer <s.hauer@pengutronix.de>
|Date:   Wed Jul 4 23:41:13 2012 +0200
|
|    mem md: bail out without arguments
|
|    Without arguments the 'md' command defaults to show address 0 which
|    likely results in a NULL pointer exception, so only three keystrokes
|    are necessary to crash barebox. Show usage instead if 'md' is invoked
|    without arguments, so that it at least requires an address to be given
|    to crash barebox. This increases the stability of barebox by 66%. Hurray!

barebox does not crash any longer when a plain 'md' without additional arguments
is exectuted. However, doing a 'md -s /dev/nor0' was a standard usecase which now
does not work anymore.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>