[SCSI] libcxgbi: common library for cxgb3i and cxgb4i

[PATCH v5 1/3] libcxgbi: common library for cxgb3i and cxgb4i

From: Karen Xie <kxie@chelsio.com>

Extracts common functions to libcxgbi.
Signed-off-by: Karen Xie <kxie@chelsio.com>
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>