[IA64] put kdump_find_rsvd_region in __init

kdump_find_rsvd_region() is only called by
reserve_memory() which is in __init, so it seems that
kdump_find_rsvd_region() should also be in there.

Signed-off-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Tony Luck <tony.luck@intel.com>