staging: rtl8723bs: Remove rtw_hal_c2h_evt_read()

Modify call sites of rtw_hal_c2h_evt_read to call c2h_evt_read_88xx
instead, as rtw_hal_c2h_evt_read does nothing except call
c2h_evt_read_88xx.
Remove function rtw_hal_c2h_evt_read as it is now not necessary.
Issue found with Coccinelle.

Signed-off-by: Nishka Dasgupta <nishkadg.linux@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>