qla2xxx: fix kernel NULL pointer access

This patch is to fix regression added by commit id
51a07f84.

When allocating memory for new session original patch does
not assign vha to op->vha resulting into NULL pointer
access during qlt_create_sess_from_atio().

Cc: <stable@vger.kernel.org>
Signed-off-by: Himanshu Madhani <himanshu.madhani@qlogic.com>
Signed-off-by: Saurav Kashyap <saurav.kashyap@qlogic.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>