configs: omap5_pyra: add fastboot support

Add fastboot support for the Pyra

Note for this to work best, the partition table should be GPT and labeled. The following process allows the SPL, U-Boot, boot, and rootfs to be individually flashed using fastboot.

sudo sgdisk -Z /dev/mmcblk0
sudo sgdisk -a 1 -n 1:256:+128K -t 0:8300 -c 0:"spl"        /dev/mmcblk0
sudo sgdisk -a 1 -n 2:768:+768K -t 0:8300 -c 0:"bootloader" /dev/mmcblk0
sudo sgdisk -a 1 -n 3:0:+256M   -t 0:8300 -c 0:"boot"       /dev/mmcblk0
sudo sgdisk -a 1 -n 4:0:0       -t 0:8300 -c 0:"rootfs"     /dev/mmcblk0
sudo sgdisk -p /dev/mmcblk0
sync