Add WB/UC check for early_ioremap

On ia64 system, the function early_ioremap returned an uncached memory
reference without checking whether this was consistent with existing
mappings. This causes efi error and the kernel failed during boot.  Add a
check to test whether memory has EFI_MEMORY_WB set.  Use the function
kern_mem_attribute() in early_iomap() function to provide appropriate
cacheable or uncacheable mapped address.

See the document Documentation/ia64/aliasing.txt for more details.

Signed-off-by: Li, Zhen-Hua <zhen-hual@hp.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>