UPSTREAM: regulator: rk808: Migrate to regulator core's simplified DT parsing code

UPSTREAM: regulator: rk808: Migrate to regulator core's simplified DT parsing code

A common simplified DT parsing code for regulators was introduced in
commit a0c7b164ad11 ("regulator: of: Provide simplified DT parsing
method")

While at it also added RK8XX_DESC and RK8XX_DESC_SWITCH macros for the
regulator_desc struct initialization. This just makes the driver more compact.

Change-Id: I5c1211decf37d27a68167be9b6354834532cc87b
Signed-off-by: Wadim Egorov <w.egorov@phytec.de>
Acked-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
(cherry picked from commit 9e9daa0a67d59df432664cdca1cf4659057fd00c)
Signed-off-by: Elaine Zhang <zhangqing@rock-chips.com>