xen: Drop un-informative message during boot

xen: Drop un-informative message during boot

On systems that are not booted as a Xen domain, the xenfs driver prints
the following message during boot.

[    3.460595] xenfs: not registering filesystem on non-xen platform

As the user chose not to boot a Xen domain, this message does not
provide useful information. Drop this message.

Signed-off-by: Punit Agrawal <[email protected]>
Cc: Boris Ostrovsky <[email protected]>
Cc: Juergen Gross <[email protected]>
Reviewed-by: Boris Ostrovsky <[email protected]>
Signed-off-by: Juergen Gross <[email protected]>