drivers/scsi/sd.c: use ida_simple_get() and ida_simple_remove() in place of boilerpla...

drivers/scsi/sd.c: use ida_simple_get() and ida_simple_remove() in place of boilerplate code

Some mangling of errors was necessary to maintain current interface.

Signed-off-by: Jonathan Cameron <jic23@cam.ac.uk>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Tejun Heo <tj@kernel.org>
Cc: Guenter Roeck <guenter.roeck@ericsson.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>