soc/intel/quark: Add missing breaks

Add missing breaks in reg_access.c.

TEST=Build and run on Galileo Gen2

Found-by: Converity Scan #1361261

Change-Id: I8be57f0758e5918a605e20ab9002747e0cc958e0
Signed-off-by: Lee Leahy <leroy.p.leahy@intel.com>
Reviewed-on: https://review.coreboot.org/16069
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Tested-by: build bot (Jenkins)

src/soc/intel/quark/reg_access.c

@@ -163,9 +163,11 @@ static void reg_cpu_cr_write(uint32_t reg_address, CRx_TYPE value)
 
 	case 0:
 		write_cr0(value);
+		break;
 
 	case 4:
 		write_cr4(value);
+		break;
 	}
 }