staging: unisys: visorbus: add checks for probe, remove, pause and resume in...

staging: unisys: visorbus: add checks for probe, remove, pause and resume in visorbus_register_visor_driver

Added checks for functions probe, remove, pause and resume in
visorbus_register_visor_driver() and removed these checks from
the individual functions itself.

Signed-off-by: Sameer Wadgaonkar <sameer.wadgaonkar@unisys.com>
Signed-off-by: David Kershner <david.kershner@unisys.com>
Reviewed-by: David Binder <david.binder@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>