Wip/martyn/u boot installer

overlays/installer-mx6qsabrelite/boot.cmd

@@ -8,5 +8,10 @@ echo "Erasing SPI_NOR"
 sf erase 0x0 0xc0000
 echo "Writing U-Boot to SPI-NOR"
 sf write 0x12000000 0x400 0xc0000
-echo "Rebooting"
-reset
+echo ""
+echo '+-----------------------------------------------------------------+'
+echo '|                  U-Boot installation complete                   |'
+echo '|                                                                 |'
+echo '| Please remove the SD Card and power cycle the board to continue |'
+echo '+-----------------------------------------------------------------+'
+loop 0 0