OMAP2: powerdomain: Add break in switch statement

Add a missing break at end of switch statement. At the moment it is a
fall through to WARN_ON(1) and return -EEXIST.

Signed-off-by: Thomas Weber <weber@corscience.de>
Acked-by: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/mach-omap2/powerdomain.c

@@ -875,6 +875,7 @@ int pwrdm_read_mem_retst(struct powerdomain *pwrdm, u8 bank)
 		break;
 	case 4:
 		m = OMAP_MEM4_RETSTATE_MASK;
+		break;
 	default:
 		WARN_ON(1); /* should never happen */
 		return -EEXIST;