fru: server 3.0: Add option to skip validating lanes

Summary:
For main PCIe clusters, the lanes associated with a slot should equal
x8 or x16 if combined. PCIe utility clusters don't follow this though.
For example, platform 30's utility cluster bifurcation is 1x1 + 1x4
for a total of 5.

When a bus number isn't provided via the configuration file, don't
require that the lanes for a slot add up to x8 or x16.

Tested:
Successfully set the bifurcation info to 'x1x4' for a slot on platform
30.

Google-Bug-Id: 435526024
Change-Id: Ia7b8533f6e98f38e3e36dd1d334fbbe9cdd85d36
Signed-off-by: Kyle Nieman <kyle.nieman@fii-na.corp-partner.google.com>