Revert "mimxrt/machine_uart: Implement a Python UART IRQ handler."

This reverts commit b7fa4e2.

Author: iabdalkader

ports/mimxrt/Makefile

@@ -133,6 +133,7 @@ SRC_HAL_IMX_C += \
 	$(MCU_DIR)/drivers/fsl_lpi2c.c \
 	$(MCU_DIR)/drivers/fsl_lpspi.c \
 	$(MCU_DIR)/drivers/fsl_lpspi_edma.c \
+	$(MCU_DIR)/drivers/fsl_lpuart.c \
 	$(MCU_DIR)/drivers/fsl_pit.c \
 	$(MCU_DIR)/drivers/fsl_pwm.c \
 	$(MCU_DIR)/drivers/fsl_sai.c \