staging: rtl8723bs: Change camel case to snake case in 'rtl8723bs_recv.c'.

Linux kernel coding style dictates the use of snake case for variable
naming.

Signed-off-by: Quytelda Kahja <quytelda@tamalin.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>