rtl2800usb: Fix incorrect storage of MAC address on big-endian platforms

The eeprom data is stored in little-endian order in the rt2x00 library.
As it was converted to cpu order in the read routines, the data need to
be converted to LE on a big-endian platform.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Stable <stable@kernel.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>