ssb: use "break" on default case to prevent warning

Having an empty default: case in a switch statement causes a warning
(when using Clang; I don't see the warning when using gcc),
so add a "break;" to the default case to prevent the warning:

drivers/ssb/main.c:1149:2: warning: label at end of compound statement is a C2x extension [-Wc2x-extensions]

Fixes: e27b02e23a ("ssb: drop use of non-existing CONFIG_SSB_DEBUG symbol")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202403130717.TWm17FiD-lkp@intel.com/
Cc: Michael Büsch <m@bues.ch>
Cc: linux-wireless@vger.kernel.org
Cc: Kalle Valo <kvalo@kernel.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: llvm@lists.linux.dev
Acked-by: Michael Büsch <m@bues.ch>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://msgid.link/20240313001305.18820-1-rdunlap@infradead.org

drivers/ssb/main.c

@@ -1146,6 +1146,7 @@ u32 ssb_dma_translation(struct ssb_device *dev)
 				return SSB_PCI_DMA;
 		}
 	default:
+		break;
 	}
 	return 0;
 }