drm/amd/pm: return -ENOTSUPP if there is no get_dpm_ultimate_freq function

clang static analysis reports this represenative problem
amdgpu_smu.c:144:18: warning: The left operand of '*' is a garbage value
        return clk_freq * 100;
               ~~~~~~~~ ^

If there is no get_dpm_ultimate_freq function,
smu_get_dpm_freq_range returns success without setting the
output min,max parameters.  So return an -ENOTSUPP error.

Fixes: e5ef784b1e ("drm/amd/powerplay: revise calling chain on retrieving frequency range")
Signed-off-by: Tom Rix <trix@redhat.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/pm/swsmu/amdgpu_smu.c

@@ -116,7 +116,7 @@ int smu_get_dpm_freq_range(struct smu_context *smu,
 			   uint32_t *min,
 			   uint32_t *max)
 {
-	int ret = 0;
+	int ret = -ENOTSUPP;
 
 	if (!min && !max)
 		return -EINVAL;