use validator in mimx UART constructor

Author: dhalbert

ports/mimxrt10xx/common-hal/busio/UART.c

@@ -113,12 +113,9 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
     bool sigint_enabled) {
 
     self->baudrate = baudrate;
-    self->character_bits = bits;
+    self->character_bits = (uint8_t)mp_arg_validate_int_range(self->character_bits, 7, 8, MP_QSTR_bits);
     self->timeout_ms = timeout * 1000;
 
-    if (self->character_bits != 7 && self->character_bits != 8) {
-        mp_arg_validate_int_range(self->character_bits, 7, 8, MP_QSTR_bits);
-    }
 
     DBGPrintf(&mp_plat_print, "uart_construct: tx:%p rx:%p rts:%p cts:%p rs485:%p\n", tx, rx, rts, cts, rs485_dir);