clk: mediatek: Initialize clk_init_data

The variable init (struct clk_init_data) is allocated on the stack.
We weren't initializing the .flags field, so it contains random junk,
which can cause all kinds of interesting issues when the flags are
parsed by clk_register.

Signed-off-by: Ricky Liang <jcliang@chromium.org>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>