PCI: remove unused AER functions

In the commit 28eb5f27, aer_osc_setup is removed but corresponding
definiton information in the aerdrv.h is missed.

Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Chen Gong <gong.chen@linux.intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>