[SCSI] libfc: fcoe_transport_create fails in single-CPU environment

Starting fcoe fails at fcoe_transport_create when attempting to allocate a
pool of 4K exchanges on a 64-bit single-CPU environment because the call to
__alloc_percpu() is greater than the max of 32K.  This patch reduces the
number of exchanges to fit within the maximum allowed space.

[ Whitespace problems fixed by Robert Love to satisfy chechpatch.pl ]

Signed-off-by: Steven Clark <sclark@crossbeam.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>