sensors: dts: cleanup usage of HAS_DTS_I2C_DEVICE

Move to new Kconfig pattern in which we use an if !HAS_DTS_I2C_DEVICE
block for the Kconfig symbols that can now come from DT generation.
This pattern is useful to allow us to define default values for the
generated symbols for build-all testing.

Fixes: #5877

Signed-off-by: Kumar Gala <kumar.gala@linaro.org>