Add main code for internal abort functionality.

The internal abort features allows the host controller to abort commands
which are still active in the controller but have not yet been sent to
the slave device.

Typically a command only spends a relatively short time in the
controller when compared to the amount of the time after it is sent to
the slave device.

Two modes of internal abort are supported:

 - device
 - individual command

For device, when the internal abort is issued all commands in the host
for that device are aborted.  For a single command, only that command is
aborted if it is still in the host.

In HW the internal abort command is executed similar to any other sort
of command, like SSP.
Signed-off-by: John Garry <john.garry@huawei.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>