staging: rtl8712: changed u32 to __le32

Fixed sparse warnings.
Deleted cpu_to_le32() for enum. I'm not sure why it was there.

Signed-off-by: Jannik Becher <becher.jannik@gmail.com>
Tested-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>