ARM: msm: Remove custom clk_set_flags() API

Nobody is using this API upstream and it's just contributing
cruft. Remove it so the MSM clock API is closer to the generic
struct clock API.

Acked-by: Saravana Kannan <skannan@codeaurora.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: David Brown <davidb@codeaurora.org>