ACPI: property: Support using strings in reference properties

In order to allow referencing data nodes directly, which is not possible
currently, add support for representing references in device properties
as strings (relative or absolute name paths).  For example, after this
change, the "mipi-img-flash-leds" property in the ASL snippet below will
be treated as a proper reference to the LED0 object under LEDD.

 Package ()
 {
     "mipi-img-flash-leds",  "\\_SB.PCI0.I2C2.LEDD.LED0",
 }

 Device (LEDD)
 {
     Name (_DSD, Package ()  // _DSD: Device-Specific Data
     {
         ToUUID ("dbb8e3e6-5886-4ba6-8795-1319f52a966b"), /* Hierarchical Data Extension */,
         Package ()
         {
             Package ()
             {
                 "mipi-img-flash-led-0",
                 "LED0",
             }
         },
     })
     Name (LED0, Package ()  // _DSD: Device-Specific Data
     {
         ToUUID ("daffd814-6eba-4d8c-8a91-bc9bbf4aa301") /* Device Properties */,
         Package ()
         {
             Package ()
             {
                 "mipi-img-max-current",
                 1000000,
             }
         }
     })
 }

Also remove the mechanism allowing data nodes to be referenced
indirectly, with the help of an object reference pointing to the
"ancestor" device and a path relative to it (this mechanism is not
expected to be in use in any production platform firmware in the field).

Note that this change allows also using strings for referencing device
objects, in addition to object references that have been supported
already.

While at it, add pr_fmt() macro to prefix printouts and update
copyright.

Co-developed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Sakari Ailus <sakari.ailus@linux.intel.com>