leds: Fix reference file name of documentation

In commit 56b01acc1c79a ("dt-bindings: gpio: fairchild,74hc595:
Convert to json-schema"), gpio-74x164.txt was deleted and replaced
by fairchild,74hc595.yaml. Fix the reference file name.

Signed-off-by: Wan Jiabing <[email protected]>
Acked-by: Pavel Machek <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Rob Herring <[email protected]>
2 files changed