MIPS: lantiq: add ipi handlers to make vsmp work

Add IPI handlers to the interrupt code. This patch makes MIPS_MT_SMP work
on lantiq socs. The code is based on the malta implementation.

Signed-off-by: John Crispin <blogic@openwrt.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/3704/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/lantiq/prom.c

@@ -68,4 +68,9 @@ void __init prom_init(void)
 	soc_info.sys_type[LTQ_SYS_TYPE_LEN - 1] = '\0';
 	pr_info("SoC: %s\n", soc_info.sys_type);
 	prom_init_cmdline();
+
+#if defined(CONFIG_MIPS_MT_SMP)
+	if (register_vsmp_smp_ops())
+		panic("failed to register_vsmp_smp_ops()");
+#endif
 }