Formalise globbing support for deviceinfo_dtb
@jenneron discovered in pmaports!4250 (comment 1470930432) that boot-deploy supports globbing for the deviceinfo_dtb
variable, which is a very useful feature for devices with a lot of dtbs where listing them all is unwieldy on one line. This is effectively due to an implementation detail (find
supporting globbing), which isn't a good thing to rely on in case someone changes the implementation. As such, I think it would be good to formalise that this supports globbing by documenting it and also writing a test that ensures it stays working.