tools: imx8m_image: Support ddr3 firmware

Some boards use ddr3, not ddr4, so we need to check ddr3 firmware.

Signed-off-by: Ariel D'Alessandro <ariel.dalessandro@collabora.com>
diff --git a/tools/imx8m_image.sh b/tools/imx8m_image.sh
index ba60104..4ab3116 100755
--- a/tools/imx8m_image.sh
+++ b/tools/imx8m_image.sh
@@ -41,6 +41,13 @@
 		cat spl/u-boot-spl-pad.bin ddr4_1d_fw.bin ddr4_2d_fw.bin > spl/u-boot-spl-ddr.bin
 		rm -f ddr4_1d_fw.bin ddr4_2d_fw.bin ddr4_imem_1d_pad.bin ddr4_dmem_1d_pad.bin ddr4_imem_2d_pad.bin spl/u-boot-spl-pad.bin
 	fi
+	if [ -f ddr3_imem_1d.bin ]; then
+		objcopy -I binary -O binary --pad-to 0x8000 --gap-fill=0x0 ddr3_imem_1d.bin ddr3_imem_1d_pad.bin
+		cat ddr3_imem_1d_pad.bin ddr3_dmem_1d.bin > ddr3_1d_fw.bin
+		dd if=spl/u-boot-spl.bin of=spl/u-boot-spl-pad.bin bs=4 conv=sync
+		cat spl/u-boot-spl-pad.bin ddr3_1d_fw.bin > spl/u-boot-spl-ddr.bin
+		rm -f ddr3_1d_fw.bin ddr3_imem_1d_pad.bin spl/u-boot-spl-pad.bin
+	fi
 fi
 
 exit 0