staging: rtl8723bs: os_dep: Remove variable pos

Remove variable pos as it is not used after (or before) being assigned a
value.
Issue found with Coccinelle.

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