rtlwifi: rtl8192c: Remove rtl8192c_phy_scan_operation_backup()

Drivers rtl8192ce and rtl8192cu no longer rely on this routine. It is removed.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>