[SCSI] use scatter lists for all block pc requests and simplify hw handlers
[SCSI] use scatter lists for all block pc requests and simplify hw handlers

Here's the proof of concept for this one.  It converts scsi_wait_req to
do correct REQ_BLOCK_PC submission (and works nicely in my setup).

The final goal should be to eliminate struct scsi_request, but that
can't be done until the character submission paths of sg and st are also
modified.

There's some loss of functionality to this: retries are no longer
controllable (except by setting REQ_FASTFAIL) and the wait_req API needs
to be altered, but it looks very nice.

Signed-off-by: James Bottomley <407b36959ca09543ccda8f8e06721c791bc53435@SteelEye.com>

KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs