aer-inject: new package

aer-inject: new package

aer-inject allows to inject PCIE AER errors on the software level into
a running Linux kernel. This is intended for validation of the PCIE
driver error recovery handler and PCIE AER core handler.

Signed-off-by: Tiago Brusamarello <tiago.brusamarello@datacom.ind.br>
[Thomas:
 - tweak commit log
 - rewrap Config.in help text
 - remove useless AER_INJECT_MAKE_OPTS variable, use
   TARGET_CONFIGURE_OPTS directly
 - add missing newline at end of .mk file.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>