[SCSI] fcoe: cleanup cpu selection for incoming requests

Cleanup to:

- have selection for all types of frames, not just FCP.
- remove redundant cpu_online check once fcoe_select_cpu called
  as this is not required since later code flow check for offlined
  cpu.
- Simplify fcoe_select_cpu() by removing unnecessary checks to
  skip curr_cpu, this also fixes possibly infinite loop in case
  of curr_cpu is the only cpu while iterating in the loop.

This cleanup mainly applies to target as incoming request are
mostly for target, therefore Kiran has verified the patch
with target also.

Signed-off-by: Vasu Dev <vasu.dev@intel.com>
Tested-by: Kiran Patil <kiran.patil@intel.com>
Tested-by: Ross Brattain <ross.b.brattain@intel.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>