qlcnic: validate unified fw image

Validate all sections of unified fw image, before accessing them,
to avoid seg fault.

Signed-off-by: Sucheta Chakraborty <sucheta@dut6195.unminc.com>
Signed-off-by: Amit Kumar Salecha <amit.salecha@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>