staging: unisys: include: remove unused spar_channel_client_acquire_os

The function spar_channel_client_acquire_os is not being used so
remove it.

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>