driver core: physical_location.h remove extern from function prototypes

The kernel coding style does not require 'extern' in function prototypes
in .h files, so remove them from drivers/base/physical_location.h as
they are not needed.
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Link: https://lore.kernel.org/r/20230324122711.2664537-5-gregkh@linuxfoundation.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base/physical_location.h

@@ -8,7 +8,7 @@
 #include <linux/device.h>
 
 #ifdef CONFIG_ACPI
-extern bool dev_add_physical_location(struct device *dev);
+bool dev_add_physical_location(struct device *dev);
 extern const struct attribute_group dev_attr_physical_location_group;
 #else
 static inline bool dev_add_physical_location(struct device *dev) { return false; };