pcieaer doc: update the link

The original link is empty, replace it.

Signed-off-by: Cao jin <[e-mail]>
Signed-off-by: Jonathan Corbet <[e-mail]>

Documentation/PCI/pcieaer-howto.txt

···
 
 Then, you need a user space tool named aer-inject, which can be gotten
 from:
-    http://www.kernel.org/pub/linux/utils/pci/aer-inject/
+    https://git.kernel.org/cgit/linux/kernel/git/gong.chen/aer-inject.git/
 
 More information about aer-inject can be found in the document comes
 with its source code.