hv: treewide: fix 'Switch empty default has no comment'

This patch add some comments after the default and before the break
in the switch statement based on MISRA-C requirement.

Signed-off-by: Shiqing Gao <shiqing.gao@intel.com>
Reviewed-by: Junjie Mao <junjie.mao@intel.com>

hypervisor/debug/shell.c

@@ -194,6 +194,12 @@ static void shell_handle_special_char(uint8_t ch)
 		(void) shell_getc();
 		break;
 	default:
+		/*
+		 * Only the Escape character is treated as special character.
+		 * All the other characters have been handled properly in
+		 * shell_input_line, so they will not be handled in this API.
+		 * Gracefully return if prior case clauses have not been met.
+		 */
 		break;
 	}
 }

hypervisor/debug/vuart.c

@@ -205,6 +205,11 @@ static void vuart_write(__unused struct vm_io_handler *hdlr,
 		vu->scr = value;
 		break;
 	default:
+		/*
+		 * For the offset that is not handled (either a read-only
+		 * register or an invalid register), ignore the write to it.
+		 * Gracefully return if prior case clauses have not been met.
+		 */
 		break;
 	}