Add an ISA attachement to the aic7xxx driver to handle 284X controllers.

Add an ISA attachement to the aic7xxx driver to handle 284X controllers.
The ISA probe uses an identify routine to probe all slot locations from
1 to 14 that do not conflict with other allocated resources.  This required
making aic7770.c part of the driver core when compiled as a module.

aic7xxx.c:
aic79xx.c:
aic_osm_lib.c:
        Use aic_scb_timer_start() consistently to start the watchdog timer.
        This removes a few places that verbatum copied the code in
        aic_scb_timer_start().

        During recovery processing, allow commands to still be queued to
        the controller.  The only requirement we have is that our recovery
        command be queued first - something the code already guaranteed.
        The only other change required to make this work is to prevent
        timers from being started for these newly queued commands.

Obtained-from: FreeBSD