pkg/mount/scuzz: Allow creation from File-like ref
pkg/mount/scuzz: Allow creation from File-like ref

This allows for easier integration on 3rd party libraries.

Signed-off-by: Christian Svensson <4c9a82ce72ca2519f38d0af0abbb4cecb9fceca9@cmd.nu>

u-root/u-root,u-root/u-root,u-root/u-root