MIPS: Skip IPI setup if we only have 1 CPU

If we're running on a system with only 1 possible CPU then it makes no
sense to reserve or initialise IPIs since we'll never use them. Avoid
doing so.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/16192/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/smp.c

@@ -335,6 +335,9 @@ int mips_smp_ipi_free(const struct cpumask *mask)
 
 static int __init mips_smp_ipi_init(void)
 {
+	if (num_possible_cpus() == 1)
+		return 0;
+
 	mips_smp_ipi_allocate(cpu_possible_mask);
 
 	call_desc = irq_to_desc(call_virq);