MIPS: loongson2ef: Add missing break in cs5536_isa

Fixes build error:

arch/mips/loongson2ef/common/cs5536/cs5536_isa.c:217:2: error:
unannotated fall-through between switch labels [-Werror,-Wimplicit-fallthrough]
        default:
        ^
arch/mips/loongson2ef/common/cs5536/cs5536_isa.c:217:2:
note: insert 'break;' to avoid fall-through
        default:
        ^
        break;

Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

Author: FlyGoat

arch/mips/loongson2ef/common/cs5536/cs5536_isa.c

@@ -213,7 +213,7 @@ void pci_isa_write_reg(int reg, u32 value)
 			lo |= 0x00000063;
 			_wrmsr(SB_MSR_REG(SB_ERROR), hi, lo);
 		}
-
+		break;
 	default:
 		/* ALL OTHER PCI CONFIG SPACE HEADER IS NOT IMPLEMENTED. */
 		break;