package/rauc: target rauc needs unsquashfs at runtime

package/rauc: target rauc needs unsquashfs at runtime

In order to provide info about a bundle file, e.g. running "rauc info
bundle.raucb", rauc needs to use the unsquashfs progam from the squashfs
package.

This was not documented until upstream commit 10c501c12752 ("docs:
integration: document need for 'unsquashfs' tool for 'rauc info'"), but
is already present in rauc.

Signed-off-by: Trent Piepho <tpiepho@impinj.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>