of: overlay.c: Remove comments that state the obvious, to reduce clutter

Follows recommendations in Documentation/process/coding-style.rst,
section 8, Commenting.

Some in function comments are promoted to function header comments.

Signed-off-by: Frank Rowand <frank.rowand@sony.com>
Signed-off-by: Rob Herring <robh@kernel.org>
1 file changed