drm/amdgpu: Set reference clock to 100Mhz on Renoir (v2)

Fixes the rlc reference clock used for GPU timestamps.
Value is 100Mhz.  Confirmed with hardware team.

v2: reword commit message.

Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/1480
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

drivers/gpu/drm/amd/amdgpu/soc15.c

@@ -233,6 +233,8 @@ static u32 soc15_get_xclk(struct amdgpu_device *adev)
 {
 	u32 reference_clock = adev->clock.spll.reference_freq;
 
+	if (adev->asic_type == CHIP_RENOIR)
+		return 10000;
 	if (adev->asic_type == CHIP_RAVEN)
 		return reference_clock / 4;