staging: rtl8712: Fix some Sparse endian messages

Sparse reports the following:

  CHECK   drivers/staging/rtl8712/rtl8712_xmit.c
drivers/staging/rtl8712/rtl8712_xmit.c:564:42: warning: cast from restricted __le32
drivers/staging/rtl8712/rtl8712_xmit.c:569:42: warning: cast from restricted __le32
drivers/staging/rtl8712/rtl8712_xmit.c:571:42: warning: cast from restricted __le32

Each of these cases is transferring a quantity that is little-endian. There
is no need for conversion.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>