squashfs: bump version to 4.4

squashfs: bump version to 4.4

Bump to version 4.4 and switch to github site since the kernel
repository has not been updated. See
https://github.com/plougher/squashfs-tools/blob/master/README.

Dropping patch that has been incorporated in the new release.

This version bump includes support for reproducible images. See the full
release notes for details at
https://github.com/plougher/squashfs-tools/blob/master/README-4.4

Signed-off-by: Clayton Shotwell <clayton.shotwell@rockwellcollins.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>