[SCSI] bnx2i: Added mutex lock protection to conn_get_param

Added net_dev mutex lock protection before accessing the csk
parameters.

Signed-off-by: Eddie Wai <eddie.wai@broadcom.com>
Reviewed-by: Benjamin Li <benli@broadcom.com>
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>