mimxrt/Makefile: Use a specific fsl_flexspi_nor_boot.c for mimxrt1062.

This one sets the flash image length properly for the teensy loader, such
that the file system is not erased.  It was already set in commit
8e54225140 but got lost when the MIMXRT1176
board was added.

Signed-off-by: robert-hh <robert@hammelrath.com>

ports/mimxrt/Makefile

@@ -140,7 +140,13 @@ SRC_HAL_IMX_C += \
 	$(MCU_DIR)/drivers/fsl_snvs_lp.c \
 	$(MCU_DIR)/drivers/fsl_wdog.c \
 	$(MCU_DIR)/system_$(MCU_SERIES)$(MCU_CORE).c \
-	$(MCU_DIR)/xip/fsl_flexspi_nor_boot.c \
+
+# Use a specific boot header for 1062 so the Teensy loader doesn't erase the filesystem.
+ifeq ($(MCU_SERIES), MIMXRT1062)
+SRC_HAL_IMX_C += hal/fsl_flexspi_nor_boot.c
+else
+SRC_HAL_IMX_C += $(MCU_DIR)/xip/fsl_flexspi_nor_boot.c
+endif
 
 ifeq ($(MICROPY_HW_SDRAM_AVAIL),1)
 SRC_HAL_IMX_C += $(MCU_DIR)/drivers/fsl_semc.c