GenWQE: Add sysfs interface for bitstream reload

This patch adds an interface on sysfs for userspace to request a card
bitstream reload. It sets the appropriate register and try to perform a
fundamental reset on the PCIe slot for the card to reload the bitstream
from the chosen partition.

Signed-off-by: Kleber Sacilotto de Souza <klebers@linux.vnet.ibm.com>
Acked-by: Frank Haverkamp <haver@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>