clk: Assert prepare_lock in clk_core_get_boundaries

This function iterates the clk consumer list on clk_core so it must be
called under prepare_lock. This is already done by all callers but add a
lockdep assert to check anyway.
Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
Link: https://lkml.kernel.org/r/29453ee8e820457d87a8faf9d496390e59c6826f.1562073871.git.leonard.crestez@nxp.comSigned-off-by: Stephen Boyd <sboyd@kernel.org>

drivers/clk/clk.c

@@ -593,6 +593,8 @@ static void clk_core_get_boundaries(struct clk_core *core,
 {
 	struct clk *clk_user;
 
+	lockdep_assert_held(&prepare_lock);
+
 	*min_rate = core->min_rate;
 	*max_rate = core->max_rate;