PCI/AER: Remove aerdriver.nosourceid kernel parameter

The aerdriver.nosourceid kernel parameter was intended for working around
broken chipsets don't supply the source ID for AER events.  We recently
added PCI_BUS_FLAGS_NO_AERSID, which can be set by quirks for the same
purpose.

Remove the aerdriver.nosourceid kernel parameter.  For anything other than
debugging, asking users to find and use kernel parameters is a poor user
experience.  Instead, we should add PCI_BUS_FLAGS_NO_AERSID quirks for any
hardware that needs it.

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