logging: fix if else if constructs missing final else

The logging subsytsem had if else if constructs without final
else statement. This commit adds else {} to comply with
coding guideline 15.7.

Signed-off-by: Jennifer Williams <jennifer.m.williams@intel.com>

subsys/logging/log_backend_rtt.c

@@ -222,6 +222,7 @@ static int data_out_block_mode(uint8_t *data, size_t length, void *ctx)
 		} else if (host_present) {
 			retry_cnt--;
 			on_failed_write(retry_cnt);
+		} else {
 		}
 	} while ((ret == 0) && host_present);