regulator: axp20x: AXP806: Fix dcdcb being set instead of dcdce

A typo or copy-paste bug means that the register access intended for
regulator dcdce goes to dcdcb instead. This patch corrects it.

Fixes: 2ca342d3 (regulator: axp20x: Support AXP806 variant)
Signed-off-by: Rask Ingemann Lambertsen <rask@formelder.dk>
Acked-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org