rtlwifi: rtl8192ce: remove duplicated function '_rtl92ce_phy_set_rf_sleep'

This function exists in phy_common.c as '_rtl92c_phy_set_rf_sleep'.
Switch to the one in common file.

Signed-off-by: Lu Jicong <jiconglu58@gmail.com>
Acked-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220306090846.28523-1-jiconglu58@gmail.com