[aacraid] Add missing aac_unmap_command() call for SYNC mode

[luporl]

Summary

On a PowerPC64 with an Adaptec RAID Controller with PCI device ID 0x028d, after several read/write operations, the kernel was panic'ing in bus_dmamap_sync().
This was due to a missing aac_unmap_command() in the SYNC path.

There is a work in progress (PR 237463) to make aacraid driver compatible with big-endian/PowerPC, in which this issue was found.

[emaste]

Yes, the similar path in aac.c has

			aac_remove_busy(cm);
 			aac_unmap_command(cm);

[luporl]

In D23668#525565, @emaste wrote:

Yes, the similar path in aac.c has

			aac_remove_busy(cm);
 			aac_unmap_command(cm);

Right, but as in aacraid.c sync commands don't call aac_enqueue_busy(cm), aac_remove_busy(cm) should not be called when they complete.