staging: rtlwifi: rtl8822be: Remove functions

Remove functions _rtl8822be_set_fw_ps_rf_on and
rtl8822be_fw_clk_off_timer_callback as they do not appear in the results
of `git grep` and the driver can be compiled without them.

Signed-off-by: Nishka Dasgupta <nishka.dasgupta@yahoo.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>