[SCSI] 3ware 8000 serialize reset code

The attached patch updates the 3ware 8000 driver:

- Free irq handler in __tw_shutdown().
- Turn on RCD bit for caching mode page.
- Serialize reset code.

Signed-off-by: Adam Radford <linuxraid@amcc.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>