ASoC: L3 bus: Add default gpio ops

This adds aptional GPIO bit-bang based callback implementations
for setting CLK, DATA and MODE L3 bus lines.  It is added here
to avoid possible duplicate implementations across users of
the bus.

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mark Brown <broonie@kernel.org>