staging: rtl8723bs: hal: sdio_halinit.c: Remove variables

Remove the variables RegRATR and RegRRSR as they are never used after
initialisation and assignment.
Issue found with Coccinelle.

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