PCI/AER: Update aer-inject URL

The link to the aer-inject referenced leads to an empty repo and seems no
longer used. Replace it with the link mentioned in
Documentation/PCI/pcieaer-howto.rst.

Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Yicong Yang <[e-mail]>
Signed-off-by: Bjorn Helgaas <[e-mail]>

drivers/pci/pcie/Kconfig

···
 	  error injection can fake almost all kinds of errors with the
 	  help of a user space helper tool aer-inject, which can be
 	  gotten from:
-	     https://www.kernel.org/pub/linux/utils/pci/aer-inject/
+	     https://git.kernel.org/cgit/linux/kernel/git/gong.chen/aer-inject.git/
 
 #
 # PCI Express ECRC

drivers/pci/pcie/aer_inject.c

···
  * trigger various real hardware errors. Software based error
  * injection can fake almost all kinds of errors with the help of a
  * user space helper tool aer-inject, which can be gotten from:
- *   https://www.kernel.org/pub/linux/utils/pci/aer-inject/
+ *   https://git.kernel.org/cgit/linux/kernel/git/gong.chen/aer-inject.git/
  *
  * Copyright 2009 Intel Corporation.
  *     Huang Ying <[e-mail]>