Parse all device.map files under /boot

The device_map.aug lense is capable of parsing device.map files from grub and grub2 environments (the format is identical). However, some distributions (such as SUSE) place grub2 device.map files in /boot/grub2 instead of /boot/grub. This patch causes the lense to find this file under any /boot subdirectory. 

(This wildcard approach seems more appropriate than adding /boot/grub2/device.map to the incl list, but either one works.)