Revert "mfd: axp20x: Allow multiple regulators"

As Chris and Vasily reported, the attempt to support multiple AXP PMICs
in one system [1] breaks some of the battery and charging functionality
on devices with AXP PMICs. The reason is that the drivers now fail to get
the correct IIO channel for the ADC component, as the current code seems
to rely on the zero-based enumeration of the regulator devices.
A fix is possible, but not trivial, as it requires some rework in the AXP
MFD driver, which cannot be fully reviewed or tested in time for the
6.13 release.

So revert this patch for now, to avoid regressions on battery powered
devices. This patch was really only necessary for devices with two
PMICs, support for which is not mainline yet anyway, so we don't lose
any functionality.

This reverts commit e37ec32.

[1] https://lore.kernel.org/linux-sunxi/20241007001408.27249-4-andre.przywara@arm.com/

Reported-by: Chris Morgan <macroalpha82@gmail.com>
Closes: https://lore.kernel.org/linux-sunxi/675489c1.050a0220.8d73f.6e90@mx.google.com/
Reported-by: Vasily Khoruzhick <anarsoul@gmail.com>
Closes: https://lore.kernel.org/linux-sunxi/CA+E=qVf8_9gn0y=mcdKXvj2PFoHT2eF+JN=CmtTNdRGaSnpgKg@mail.gmail.com/
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Acked-by: Chen-Yu Tsai <wens@csie.org>
Link: https://lore.kernel.org/r/20250108164359.2609078-1-andre.przywara@arm.com
Signed-off-by: Lee Jones <lee@kernel.org>

Author: Andre-ARM

drivers/mfd/axp20x.c

@@ -1445,7 +1445,7 @@ int axp20x_device_probe(struct axp20x_dev *axp20x)
 		}
 	}
 
-	ret = mfd_add_devices(axp20x->dev, PLATFORM_DEVID_AUTO, axp20x->cells,
+	ret = mfd_add_devices(axp20x->dev, PLATFORM_DEVID_NONE, axp20x->cells,
 			      axp20x->nr_cells, NULL, 0, NULL);
 
 	if (ret) {