platform/x86/amd/pmf: Add missing __iomem attribute to policy_base

The value of policy_base is the return value of a devm_ioremap call,
which returns a __iomem pointer instead of an regular pointer.
Add the missing __iomem attribute.

Compile-tested only.

Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Link: https://lore.kernel.org/r/20240223163901.13504-1-W_Armin@gmx.de


Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>