[MIPS] Malta: Include <linux/irq.h for cp0_compare_irq / cp0_perfcount_irq.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/mips-boards/malta/malta_smtc.c

@@ -1,6 +1,7 @@
 /*
  * Malta Platform-specific hooks for SMP operation
  */
+#include <linux/irq.h>
 #include <linux/init.h>
 
 #include <asm/mipsregs.h>