powerpc/mpic: Fix ambiguous else statement

This fixes the following warning, introduced by commit
475ca391 (mpic: Deal with bogus NIRQ
in Feature Reporting Register):

  CC      arch/powerpc/sysdev/mpic.o
arch/powerpc/sysdev/mpic.c: In function 'mpic_alloc':
arch/powerpc/sysdev/mpic.c:1146: warning: suggest explicit braces to avoid ambiguous 'else'
Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Acked-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/sysdev/mpic.c

@@ -1143,13 +1143,14 @@ struct mpic * __init mpic_alloc(struct device_node *node,
 	greg_feature = mpic_read(mpic->gregs, MPIC_INFO(GREG_FEATURE_0));
 	mpic->num_cpus = ((greg_feature & MPIC_GREG_FEATURE_LAST_CPU_MASK)
 			  >> MPIC_GREG_FEATURE_LAST_CPU_SHIFT) + 1;
-	if (isu_size == 0)
+	if (isu_size == 0) {
 		if (flags & MPIC_BROKEN_FRR_NIRQS)
 			mpic->num_sources = mpic->irq_count;
 		else
 			mpic->num_sources =
 				((greg_feature & MPIC_GREG_FEATURE_LAST_SRC_MASK)
 				 >> MPIC_GREG_FEATURE_LAST_SRC_SHIFT) + 1;
+	}
 
 	/* Map the per-CPU registers */
 	for (i = 0; i < mpic->num_cpus; i++) {