ehea: add kdump support

This patch adds kdump support to the ehea driver. As the firmware doesn't free
resource handles automatically, the driver has to run an as simple as possible
free resource function in case of a crash shutdown. The function iterates over
two arrays freeing all resource handles which are stored there. The arrays are
kept up-to-date during normal runtime. The crash handler fn is triggered by the
recently introduced PPC crash shutdown reg/unreg functions.

Signed-off-by: Thomas Klein <tklein@de.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>