dt-bindings: backlight: Update Lee Jones' email address

Going forward, I'll be using my kernel.org for upstream work.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Lee Jones <lee@kernel.org>
Acked-by: Pavel Machek <pavel@ucw.cz>
Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
Link: https://lore.kernel.org/r/20220714112533.539910-7-lee@kernel.org