eHEA: Introducing support vor DLPAR memory add

This patch adds support for DLPAR memory add to the eHEA driver. To detect
whether memory was added the driver uses its own memory mapping table and
checks for kernel addresses whether they're located in already known memory
sections. If not the function ehea_rereg_mrs() is triggered which performs
a rebuild of the mapping table and a re-registration of the global memory
region.

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