staging: dgap: get rid of DGAP_LOCK and DGAP_UNLOCK macros

This patch replaces the DGAP_LOCK and DGAP_UNLOCK macros with
spin_lock_irqsave spin_unlock_irqrestore.

Signed-off-by: Mark Hounschell <markh@compro.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>