irqchip/crossbar: Fix incorrect type of local variables

The max and entry variables are unsigned according to the dt-bindings.
Fix following 3 sparse issues (-Wtypesign):

  drivers/irqchip/irq-crossbar.c:222:52: warning: incorrect type in argument 3 (different signedness)
  drivers/irqchip/irq-crossbar.c:222:52:    expected unsigned int [usertype] *out_value
  drivers/irqchip/irq-crossbar.c:222:52:    got int *<noident>

  drivers/irqchip/irq-crossbar.c:245:56: warning: incorrect type in argument 4 (different signedness)
  drivers/irqchip/irq-crossbar.c:245:56:    expected unsigned int [usertype] *out_value
  drivers/irqchip/irq-crossbar.c:245:56:    got int *<noident>

  drivers/irqchip/irq-crossbar.c:263:56: warning: incorrect type in argument 4 (different signedness)
  drivers/irqchip/irq-crossbar.c:263:56:    expected unsigned int [usertype] *out_value
  drivers/irqchip/irq-crossbar.c:263:56:    got int *<noident>

Signed-off-by: Franck Demathieu <fdemathieu@gmail.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>