ACPI: fix acpi_os_map_memory()

ACPI: fix acpi_os_map_memory()

It using map_domain_page() was entirely wrong. Use __acpi_map_table()
instead for the time being, with locking added as the mappings it
produces get replaced with subsequent invocations. Using locking in
this way is acceptable here since the only two runtime callers are
acpi_os_{read,write}_memory(), which don't leave mappings pending upon
returning to their callers.

Also fix __acpi_map_table()'s first parameter's type - while benign for
unstable, backports to pre-4.3 trees will need this.

Signed-off-by: Jan Beulich <jbeulich@suse.com>