ixgbe: prevent PBA read over eeprom word size

DPDK commit message

net/ixgbe/base: prevent untrusted loop bound
Added length check against EEPROM size in words to prevent untrusted
loop bound reported by static code analysis.

Signed-off-by: Dawid Zielinski <dawid.zielinski@intel.com>

Obtained from: DPDK (6b58617)
MFC after: 1 week