irqchip/mips-gic: Fix selection of GENERIC_IRQ_EFFECTIVE_AFF_MASK

Without SMP enabled (such as in allnoconfig), there is a Kconfig warning
because CONFIG_IRQ_EFFECTIVE_AFF_MASK is unconditionally selected by
CONFIG_MIPS_GIC:

  WARNING: unmet direct dependencies detected for GENERIC_IRQ_EFFECTIVE_AFF_MASK
    Depends on [n]: SMP [=n]
    Selected by [y]:
    - MIPS_GIC [=y]

Add a dependency on SMP to the selection, which matches all other
selections of CONFIG_IRQ_EFFECTIVE_AFF_MASK.

Fixes: 322a9063 ("irqchip/mips-gic: Multi-cluster support")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20241101-mips-fix-generic_irq_effective_aff_mask-select-v1-1-d94db6e0de0d@kernel.org