ACPI: OSL: fix __iomem type on return from acpi_os_map_generic_address()

ACPI: OSL: fix __iomem type on return from acpi_os_map_generic_address()

The pointer returned from acpi_os_map_generic_address() is
tagged with __iomem, so make the rv it is returned to also
of void __iomem * type.

Fixes the following sparse warning:

drivers/acpi/osl.c:1686:20: warning: incorrect type in assignment (different address spaces)
drivers/acpi/osl.c:1686:20:    expected void *rv
drivers/acpi/osl.c:1686:20:    got void [noderef] __iomem *

Fixes: 6915564dc5a8 ("ACPI: OSL: Change the type of acpi_os_map_generic_address() return value")
Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
[ rjw: Subject tweak, added Fixes tag ]
Link: https://patch.msgid.link/20260311105835.463030-1-ben.dooks@codethink.co.uk
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>