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>

Documentation/PCI/pcieaer-howto.txt

@@ -61,10 +61,6 @@ be initiated although firmwares have no _OSC support. To enable the
 walkaround, pls. add aerdriver.forceload=y to kernel boot parameter line
 when booting kernel. Note that forceload=n by default.
 
-nosourceid, another parameter of type bool, can be used when broken
-hardware (mostly chipsets) has root ports that cannot obtain the reporting
-source ID. nosourceid=n by default.
-
 2.3 AER error output
 When a PCI-E AER error is captured, an error message will be outputted to
 console. If it's a correctable error, it is outputted as a warning.