A lot of the arm build (especially PBL stuff) depends on section
garbage collection to be enabled. If it is disabled a lot of targets fail
to link properly. If module support is enabled garbage collection was
disabled on the premise that we throw away too many function which may be
needed in later modules.

The proper way to keep the functions around for use in modules, which
already works, is to annotate them with EXPORT_SYMBOL.

As module support is still marked as experimental I think it's reasonable
to expect users to make sure all symbols that are used by their modules
are properly annotated.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>