staging: rtl8723bs: hal: Remove unused variable

Remove local variable psdio which is declared but not used (or returned)
in its function.
Issue found with Coccinelle.

Signed-off-by: Nishka Dasgupta <nishka.dasgupta@yahoo.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>