regmap: regmap-w1: Drop unreachable code

Both init functions have a stray "return NULL" at the end which is never
reached so drop them.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Link: https://lore.kernel.org/r/20191119125837.47619-1-mika.westerberg@linux.intel.com


Signed-off-by: Mark Brown <broonie@kernel.org>