staging: rtl8188eu: Replace function beacon_timing_control()

Remove function beacon_timing_control as all it does is call
rtw_hal_bcn_related_reg_setting.
Rename rtw_hal_bcn_related_reg_setting to beacon_timing_control for
compatibility with call sites.
Issue found with Coccinelle.

Signed-off-by: Nishka Dasgupta <nishkadg.linux@gmail.com>
Link: https://lore.kernel.org/r/20190712071746.2474-3-nishkadg.linux@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>