net: ravb: Get rid of the temporary variable irq

The 4th argument of ravb_setup_irq() is used to save the IRQ number that
will be further used by the driver code. Not all ravb_setup_irqs() calls
need to save the IRQ number. The previous code used to pass a dummy
variable as the 4th argument in case the IRQ is not needed for further
usage. That is not necessary as the code from ravb_setup_irq() can detect
by itself if the IRQ needs to be saved. Thus, get rid of the code that is
not needed.

Reported-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>