drm/amdgpu: fix array out of bounds

BugLink: http://bugs.launchpad.net/bugs/1688505

commit 484f689f upstream.

When the initial value of i is greater than zero,
it may cause endless loop, resulting in array out
of bounds, fix it.

This is a port of the radeon fix to amdgpu.
Signed-off-by: tom will <os@iscas.ac.cn>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>

drivers/gpu/drm/amd/amdgpu/kv_dpm.c

@@ -2258,7 +2258,7 @@ static void kv_apply_state_adjust_rules(struct amdgpu_device *adev,
 	if (pi->caps_stable_p_state) {
 		stable_p_state_sclk = (max_limits->sclk * 75) / 100;
 
-		for (i = table->count - 1; i >= 0; i++) {
+		for (i = table->count - 1; i >= 0; i--) {
 			if (stable_p_state_sclk >= table->entries[i].clk) {
 				stable_p_state_sclk = table->entries[i].clk;
 				break;