clk: let init callback return an error code

clk: let init callback return an error code

If the init callback is allowed to request resources, it needs a return
value to report the outcome of such a request.

Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Link: https://lkml.kernel.org/r/20190924123954.31561-3-jbrunet@baylibre.com
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Acked-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>