The 0x8071 path already greys rgb_zone_* rows (and per-key) when
rgb_control is off, so the user sees that those settings have no effect
in Device mode. The 0x8070 zone settings had no such gate: led_zone_*
rows stayed active even with led_control off, implying writes that go
nowhere.
Add the 0x8070 analog — led_zone_* rows gate on led_control, mirroring
rgb_zone_* / rgb_control — wired into the same three points: initial
_apply_rgb_gates, the toggle-time re-gate, and the async-read guard in
_update_setting_item so a late read can't un-grey a blocked row.
00a6a59f9e