staging: unisys: include: Rename channel.h to visorchannel.h

In order to avoid a potential conflict with other drivers that define a
channel.h file, the s-Par channel.h file is renamed in accordance with the
surrounding driver-set namespace.

Signed-off-by: David Binder <david.binder@unisys.com>
Signed-off-by: David Kershner <david.kershner@unisys.com>
Reviewed-by: Tim Sell <timothy.sell@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>