Use extended crashkernel command line on ia64

This patch adapts IA64 to use the generic parse_crashkernel() function instead
of its own parsing for the crashkernel command line.

Because the total amount of System RAM must be known when calling this
function, efi_memmap_init() is modified to return its accumulated total_memory
variable.

Also, the crashkernel handling is moved in an own function in
arch/ia64/kernel/setup.c to make the code more readable.

[kamalesh@linux.vnet.ibm.com: build fix]
Signed-off-by: Bernhard Walle <bwalle@suse.de>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Vivek Goyal <vgoyal@in.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>