rtlwifi: Fix warnings on parisc arch

In "Build regressions/improvements in v3.0-rc2", Geert Uytterhoeven
reports a number of warnings that occur for parisc builds of rtlwifi
and dependents.

Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>