rtlwifi: Align private space in rtl_priv struct

The private array at the end of the rtl_priv struct is not aligned.
On ARM architecture, this causes an alignment trap and is fixed by aligning
that array with __align(sizeof(void *)). That should properly align that
space according to the requirements of all architectures.

Reported-by: Jason Andrews <jasona@cadence.com>
Tested-by: Jason Andrews <jasona@cadence.com>
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Stable <stable@vger.kernel.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>