drivers/misc: ipanic should have a module parameter to specify dump partition

drivers/misc: ipanic should have a module parameter to specify dump partition

BZ: 31275

Previously, dump partition was always number 6 (ie. mmcblk0p6). This
prevents repartitioning and reordering on futur boards.

This patch keeps 6 as the default, but makes the number configurable
as a module param :
 - with kernel commandline emmc_ipanic.ipanic_part_number=3 for mmcblk0p3

Change-Id: Ia14be05f4d265778118e33707fb9dc81416bce91
Signed-off-by: Robert Jarzmik <robert.jarzmik@intel.com>
Reviewed-on: http://android.intel.com:8080/48482
Tested-by: Romieu, Benoit <benoit.romieu@intel.com>
Reviewed-by: Romieu, Benoit <benoit.romieu@intel.com>
Reviewed-by: buildbot <buildbot@intel.com>
Tested-by: buildbot <buildbot@intel.com>