ACPI / glue: Split dev_is_platform() out of module for wide use

There would be useful to have in future the similar API in platform
core, as we have, for example, for PCI subsystem, to check if device
belongs to it.

Thus, split out conditional to a macro dev_is_platform() for wide use.

No functional change intended.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>