arm64: dts: allwinner: Revert SD card CD GPIO for Pine64-LTS

Commit 941432d007 ("arm64: dts: allwinner: Drop non-removable from
SoPine/LTS SD card") enabled the card detect GPIO for the SOPine module,
along the way with the Pine64-LTS, which share the same base .dtsi.

This was based on the observation that the Pine64-LTS has as "push-push"
SD card socket, and that the schematic mentions the card detect GPIO.

After having received two reports about failing SD card access with that
patch, some more research and polls on that subject revealed that there
are at least two different versions of the Pine64-LTS out there:
- On some boards (including mine) the card detect pin is "stuck" at
  high, regardless of an microSD card being inserted or not.
- On other boards the card-detect is working, but is active-high, by
  virtue of an explicit inverter circuit, as shown in the schematic.

To cover all versions of the board out there, and don't take any chances,
let's revert the introduction of the active-low CD GPIO, but let's use
the broken-cd property for the Pine64-LTS this time. That should avoid
regressions and should work for everyone, even allowing SD card changes
now.
The SOPine card detect has proven to be working, so let's keep that
GPIO in place.

Fixes: 941432d007 ("arm64: dts: allwinner: Drop non-removable from SoPine/LTS SD card")
Reported-by: Michael Weiser <michael.weiser@gmx.de>
Reported-by: Daniel Kulesz <kuleszdl@posteo.org>
Suggested-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Tested-by: Michael Weiser <michael.weiser@gmx.de>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20210414104740.31497-1-andre.przywara@arm.com

arch/arm64/boot/dts/allwinner/sun50i-a64-pine64-lts.dts

@@ -21,5 +21,5 @@
 };
 
 &mmc0 {
-	cd-gpios = <&pio 5 6 GPIO_ACTIVE_LOW>; /* PF6 push-push switch */
+	broken-cd;		/* card detect is broken on *some* boards */
 };