regulator: da9063: better fix null deref with partial DT

regulator: da9063: better fix null deref with partial DT

Two versions of the original patch were sent but V1 was merged instead
of V2 due to a mistake.

So update to V2.

The advantage of V2 is that it completely avoids dereferencing the pointer,
even just to take the address, which may fix problems with some compilers.
Both versions work on my gcc 9.4 but use the safer one.

Fixes: 98e2dd5f7a8b ("regulator: da9063: fix null pointer deref with partial DT config")
Signed-off-by: Martin Fuzzey <martin.fuzzey@flowbird.group>
Tested-by: Benjamin Bara <benjamin.bara@skidata.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20230804083514.1887124-1-martin.fuzzey@flowbird.group
Signed-off-by: Mark Brown <broonie@kernel.org>