irqchip/tango: Use irq_gc_mask_disable_and_ack_set

The only usage of the irq_gc_mask_disable_reg_and_ack() function
is by the Tango irqchip driver. This usage is replaced by the
irq_gc_mask_disable_and_ack_set() function since it provides the
intended functionality.

Fixes: 4bba6689 ("irqchip/tango: Add support for Sigma Designs SMP86xx/SMP87xx interrupt controller")
Acked-by: Mans Rullgard <mans@mansr.com>
Acked-by: Marc Gonzalez <marc_gonzalez@sigmadesigns.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Doug Berger <opendmb@gmail.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>