ACPI: APEI: EINJ: Fix kernel test sparse warnings

ACPI: APEI: EINJ: Fix kernel test sparse warnings

This patch fixes the kernel test robot warning reported here:
Link: https://lore.kernel.org/all/202410241620.oApALow5-lkp@intel.com/
Use pointers annotated with the __iomem marker for all iomem map calls,
and creates a local copy of the mapped IO memory for future access in
the code. memcpy_fromio() and memcpy_toio() are used to read/write data
from/to mapped IO memory.

Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Zaid Alali <zaidal@os.amperecomputing.com>
Link: https://patch.msgid.link/20250617193026.637510-2-zaidal@os.amperecomputing.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>