[MIPS] Misc fixes for plat_irq_dispatch functions

 o adds missing ST0_IM masks, which caused the logging of valid interrupts
   as spurious
 o stops pnx8550 to log every interrupt as spurious
 o adds cause register masks for ip22/ip32, which caused handling of masked
   interrupts
 o removes some superfluous parentheses in the SNI interrupt code

Signed-Off-By: Thiemo Seufer <ths@networkno.de>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/gt64120/ev64120/irq.c b/arch/mips/gt64120/ev64120/irq.c
index 04572b9..64e4c80 100644
--- a/arch/mips/gt64120/ev64120/irq.c
+++ b/arch/mips/gt64120/ev64120/irq.c
@@ -48,7 +48,7 @@
 
 asmlinkage void plat_irq_dispatch(void)
 {
-	unsigned int pending = read_c0_status() & read_c0_cause();
+	unsigned int pending = read_c0_status() & read_c0_cause() & ST0_IM;
 
 	if (pending & STATUSF_IP4)		/* int2 hardware line (timer) */
 		do_IRQ(4);