clk: samsung: Allow modular build of the Audio Subsystem CLKCON driver

Any clock dependencies can be properly handled with deferred probing
so we can remove core_initcall and switch to a proper loadable platform
driver module.
This change has been tested on Exynos4412 Odroid U3 based board.

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Michael Turquette <mturquette@baylibre.com>
Link: lkml.kernel.org/r/1467987300-31450-1-git-send-email-s.nawrocki@samsung.com