sensor: Introduce red and green light sensor channels

The max30101 heart rate sensor supports three types of LED channels:
red, infrared, and green. The sensor interface previously defined only a
generic "light" channel and an infrared channel, so add more specialized
red and green channels to the interface.

Jira: ZEP-720
Change-Id: I5f457c335d84cdadde71927a6eb19def3181d32a
Signed-off-by: Maureen Helm <maureen.helm@nxp.com>