Remove redundant permission requirements docs.

Methods use @RequiresPermission annotation to declare permissions.
This CL removes redundant javadoc which also state the permission reqs;
the @RequiresPermission annotation results in autogenerated permission
docs.
Let some references in the javadoc in where a permission OR a role is a
requirement to use an API, or where permissions had specific API levels
noted in the javadoc.

Test: make docs
Fixes: 137633265
Change-Id: Id1ab7090def6b1d0dbdc8d2cc8586b5341e2eb7e