ia64: add early_memremap() alias for early_ioremap()

early_ioremap() on IA64 chooses its mapping type based on the EFI
memory map. This patch adds an alias "early_memremap()" to be used
where the targeted location is memory rather than an i/o device.

Signed-off-by: Leif Lindholm <leif.lindholm@linaro.org>
Acked-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>