lspci: Clarify unknown capability IDs

lspci: Clarify unknown capability IDs

For capabilities we don't know how to decode, we print the config address,
version, and capability ID:

  Capabilities: [220 v1] #19

This doesn't clearly identify the capability ID ("19"), whether it is a
PCI-compatible Capability ID or an Extended Capability ID (although you can
infer this by whether the address is 2 or 3 digits), or the fact that the
ID is printed in hex, which makes it hard to parse this manually.

Add a label ("Capability ID" or "Extended Capability ID") and print a "0x"
prefix so it's clear the value is in hex:

  Capabilities: [220 v1] Extended Capability ID 0x19

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>