msm: board-8x60: Migrate to new clock APIs

We must call clk_prepare() before clk_enable(). Since this code
runs in process context we can just call clk_prepare_enable() to
cover both cases.

Change-Id: I707aeba4fc83723da88e5e3c402455052ca9d337
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>