lspci: Use commas more consistently

lspci: Use commas more consistently

General practice has been to use a comma after a multi-word item, but omit
commas between single-bit flags.  Do this more consistently.

Sample output changes:

  - LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk+
  + LnkCtl: ASPM Disabled; RCB 64 bytes, Disabled- CommClk+

  - DevCap2: Completion Timeout: Not Supported, TimeoutDis-, NROPrPrP-, LTR+
  + DevCap2: Completion Timeout: Not Supported, TimeoutDis- NROPrPrP- LTR+

  -          10BitTagComp-, 10BitTagReq-, OBFF Not Supported, ExtFmt-, EETLPPrefix-
  +          10BitTagComp- 10BitTagReq- OBFF Not Supported, ExtFmt- EETLPPrefix-

  -          FRS-, ARIFwd-
  +          FRS- ARIFwd-

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