clk: clamp frequency index when no threshold matches

When the requested frequency was at least every table entry, the search index
ran off the end of the table and the following access read one element past it.
Clamp the index to the last valid entry.

Signed-off-by: Liam Girdwood <liam.r.girdwood@linux.intel.com>

Author: lrgirdwo

src/lib/cpu-clk-manager.c

@@ -28,6 +28,12 @@ static int request_freq_change(unsigned int core, int freq)
 			break;
 	}
 
+	/* if no entry was larger than the requested frequency the loop runs off
+	 * the end of the table; clamp to the last valid entry before indexing
+	 */
+	if (selected_freq_id >= clk->freqs_num)
+		selected_freq_id = clk->freqs_num - 1;
+
 	/* don't change clock frequency if already using proper clock */
 	current_freq = clock_get_freq(core);
 	if (clk->freqs[selected_freq_id].freq != current_freq)