ARM: dts: bcm2837-rpi-cm3: Avoid leds-gpio probing issue

ARM: dts: bcm2837-rpi-cm3: Avoid leds-gpio probing issue

bcm2835-rpi.dtsi defines the behavior of the ACT LED, which is available
on all Raspberry Pi boards. But there is no driver for this particual
GPIO on CM3 in mainline yet, so this node was left incomplete without
the actual GPIO definition. Since commit 025bf37725f1 ("gpio: Fix return
value mismatch of function gpiod_get_from_of_node()") this causing probe
issues of the leds-gpio driver for users of the CM3 dtsi file.

  leds-gpio: probe of leds failed with error -2

Until we have the necessary GPIO driver hide the ACT node for CM3
to avoid this.

Reported-by: Fredrik Yhlen <fredrik.yhlen@endian.se>
Signed-off-by: Stefan Wahren <wahrenst@gmx.net>
Fixes: a54fe8a6cf66 ("ARM: dts: add Raspberry Pi Compute Module 3 and IO board")
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>