[nrf fromlist] drivers: serial: nrf: set default frame size and endianess

Setting frame size and endianess is now supported in UARTE HAL,
so these settings must have default values configured
to avoid compiler warnings about uninitialized fields.

Upstream PR #: 86703

Signed-off-by: Nikodem Kastelik <[email protected]>

Author: nika-nordic

drivers/serial/uart_nrfx_uarte.c

@@ -605,6 +605,12 @@ static int uarte_nrfx_configure(const struct device *dev,
 #ifdef UARTE_HAS_FRAME_TIMEOUT
 	uarte_cfg.frame_timeout = NRF_UARTE_FRAME_TIMEOUT_EN;
 #endif
+
+#if NRF_UARTE_HAS_FRAME_SIZE
+	uarte_cfg.frame_size = NRF_UARTE_FRAME_SIZE_8_BIT;
+	uarte_cfg.endian = NRF_UARTE_ENDIAN_MSB;
+#endif
+
 	nrf_uarte_configure(get_uarte_instance(dev), &uarte_cfg);
 
 	data->uart_config = *cfg;