This patch

- removes support for 2.2.x and 2.4.x without the full dma API
  (<= 2.4.13 or 2.4.9rh)
- makes sure we don't acquire or release unessecary locks around
  ->scsi_done - it's a small BH/softirq that doesn't care about
  the callers lock state
- cleans up the 2.4 vs 2.6 compat code a little
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>