In the binding example, the regulator mode 4 is shown as a valid mode,
but the driver actually only support mode 0 to 2:

This generates an error in dmesg when copy/pasting the binding example:
[    0.306080] vbuck1: invalid regulator-allowed-modes element 4
[    0.307290] vbuck2: invalid regulator-allowed-modes element 4

This commit fixes this error by removing the invalid mode from the
examples.

Fixes: 977fb5b5 ("regulator: document binding for MT6315 regulator")
Signed-off-by: Fabien Parent <fparent@baylibre.com>
Link: https://lore.kernel.org/r/20220529154613.337559-1-fparent@baylibre.comSigned-off-by: Mark Brown <broonie@kernel.org>