Adds loaders for uImages on the SD card or on a raw flash partition.
These work similarily to load_rockbox() and return a buflib alloc
and size. Booting the image is left up to the caller.
Change-Id: I0d58e8c6a61d8349bc5223431cdd06dfdf2503fa
Separate loading out into its own routine with a file name
parameter in preparation for multiboot support.
Change-Id: Ic651e9fa7738ea97789e4a9669834c4e3ef22d66
Drop init_usb(), instead initialize USB early in the main function
so the hardware is placed into a known good state after a USB boot.
The impact on boot time should be minimal.
Change-Id: I9774ddfc2c27811363bdb0c54cb0e57b5ca59d73
Add check_disk() to query the disk insertion status and prompt the
user if necessary. Use this in place of init_disk().
Perform an unconditional disk_mount_all() from the main function.
Change-Id: I9a8cc42266edf99cd15ece3aee8fa25835df04ae
