Fix formatting of camera_platform.aconfig

camera_platform.aconfig currently uses a mix of 5 spaces(?)
and 2 spaces to indent nested structures, which isn't very
ideal when working with most IDEs.

This CL makes all indents 4 spaces.

Flag: EXEMPT refactor
Bug: N/A
Test: N/A. Only formatting change.
Change-Id: I4f4c44a14ca34823969d8dae6217b15f7c01cf3a