leds: Move led_init_default_state_get() to the global header

There are users inside and outside LED framework that have implemented
a local copy of led_init_default_state_get(). In order to deduplicate
that, as the first step move the declaration from LED header to the
global one.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20230103131256.33894-3-andriy.shevchenko@linux.intel.com