sdcard: /uEnv.txt disable enable_uboot_overlays, only /boot/uEnv.txt supported

Signed-off-by: Robert Nelson <robertcnelson@gmail.com>

tools/setup_sdcard.sh

@@ -800,7 +800,8 @@ populate_boot () {
 		echo "loadxrd=echo debug: [/boot/initrd.img-\${uname_r}] ... ; load mmc 0:${media_rootfs_partition} \${rdaddr} /boot/initrd.img-\${uname_r}; setenv rdsize \${filesize}" >> ${wfile}
 		echo "loaduEnvtxt=load mmc 0:${media_rootfs_partition} \${loadaddr} /boot/uEnv.txt ; env import -t \${loadaddr} \${filesize};" >> ${wfile}
 		echo "check_dtb=if test -n \${dtb}; then setenv fdtfile \${dtb};fi;" >> ${wfile}
-		echo "loadall=run loaduEnvtxt; run check_dtb; run loadximage; run loadxrd; run loadxfdt;" >> ${wfile}
+		echo "check_uboot_overlays=if test -n \${enable_uboot_overlays}; then setenv enable_uboot_overlays ;fi;" >> ${wfile}
+		echo "loadall=run loaduEnvtxt; run check_dtb; run check_uboot_overlays; run loadximage; run loadxrd; run loadxfdt;" >> ${wfile}
 		echo "" >> ${wfile}
 		echo "mmcargs=setenv bootargs console=tty0 console=\${console} \${optargs} \${cape_disable} \${cape_enable} root=/dev/mmcblk0p${media_rootfs_partition} rootfstype=\${mmcrootfstype} \${cmdline}" >> ${wfile}
 		echo "" >> ${wfile}