ibmvfc: fix little endian issues

Added big endian annotations to relevant data structure fields, and necessary
byte swappings to support little endian builds.

Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>