Merge patch series "led: implement software blinking"

Mikhail Kshevetskiy <mikhail.kshevetskiy@iopsys.eu> says:

v2 changes:
 * Drop sw_blink_state structure, move its necessary fields to
   led_uc_plat structure.
 * Add cyclic_info pointer to led_uc_plat structure. This
   simplify code a lot.
 * Remove cyclic function search logic. Not needed anymore.
 * Fix blinking period. It was twice large.
 * Other cleanups.

v3 changes:
 * Adapt code to recent cyclic function changes
 * Move software blinking functions to separate file
 * Other small changes

v4 changes:
 * Refactoring of led_set_period() function

v5 changes
 * Fix compilation if CONFIG_LED_BLINK is not defined

v6 changes:
 * Enable LEDST_BLINK state unconditionally.
 * Function led_set_period() becomes available when CONFIG_LED_BLINK
   is disabled. This makes led code simpler.
 * Software blinking requires about 100 bytes of data for a led. It's
   not a good idea to allocate so much memory for each supported led.
   Change the code to allocate blinking data only for required leds.