drm/amdgpu: fix retry loop test

This loop will exit with "retry" set to -1 if it fails but the code
checks for if "retry" is zero.  Fix this by changing post-op to a
pre-op.  --retry vs retry--.

Fixes: e01eeffc ("drm/amd/pm: avoid driver getting empty metrics table for the first time")
Reviewed-by: Evan Quan <evan.quan@amd.com>
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/pm/swsmu/smu13/smu_v13_0_6_ppt.c

@@ -337,7 +337,7 @@ static int smu_v13_0_6_setup_driver_pptable(struct smu_context *smu)
 
 	/* Store one-time values in driver PPTable */
 	if (!pptable->Init) {
-		while (retry--) {
+		while (--retry) {
 			ret = smu_v13_0_6_get_metrics_table(smu, NULL, true);
 			if (ret)
 				return ret;