net/bnx2x: fix build with icc

net/bnx2x: fix build with icc

When bnx2x debug config enabled, icc (ICC) 17.0.0 20160721
gives the following compilation error:

.../drivers/net/bnx2x/elink.c(6682):
error #3656: variable "fw_ver1" may be used before its value is set
	PMD_DRV_LOG(DEBUG,
	^

According logic in the code, this error is a false positive,
but since this is not in the fast path, fixing compiler error by
assigning initial value to variable.

Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
Acked-by: Rasesh Mody <rasesh.mody@qlogic.com>