rtlwifi: Remove unused parameter from rtl_ps_set_rf_state()

Commit 4b9d8d67 ("rtlwifi: rtl8192cu: Remove unused parameter") reworked
this routine. Those changes were later reverted by commit d3feae41
("rtlwifi: Update power-save routines for 062814 driver").

There were two changes in commit 4b9d8d67. The first of these removed
a parameter from rtl_ps_set_rf_state() that was always false. This is the
change that is restored in the current patch. A second change that reworked
the locking is still being analyzed.

In addition to removing the unused parameter, there is no need for
rtl_ps_set_rf_state() to be exported.

Reported-by: Pavel Andrianov <andrianov@ispras.ru>
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Pavel Andrianov <andrianov@ispras.ru>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>