rtlwifi: rtl8192cu: Convert to use the new rate-mapping routine in rtlwifi

This patch also removes the now unused code from rtl8192ce/def.h.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Chaoming Li <chaoming_li@realsil.com.cn>
Signed-off-by: John W. Linville <linville@tuxdriver.com>