staging: rtl8712: Fix typo in rtl871x_io.h

Correct spelling typo "padater" to "padapter" in rtl871x_io.h

Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Acked-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>