drm/msm: Use generic bulk clock function

Remove the homebrewed bulk clock get function and replace it with
devm_clk_bulk_get_all().

Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Rob Clark <robdclark@chromium.org>