resource: Add remove_resource interface

insert_resource() and insert_resource_conflict() are called
by resource producers to insert a new resource.  When there
is any conflict, they move conflicting resources down to the
children of the new resource.  There is no destructor of these
interfaces, however.

Add remove_resource(), which removes a resource previously
inserted by insert_resource() or insert_resource_conflict(),
and moves the children up to where they were before.

__release_resource() is changed to have @release_child, so
that this function can be used for remove_resource() as well.

Also add comments to clarify that these functions are intended
for producers of resources to avoid any confusion with
request/release_resource() for consumers.

Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>