drm/msm/a6xx: Fix unknown speedbin case

When opp-supported-hw is present under an OPP node, but no form of
opp_set_supported_hw() has been called, that OPP is ignored by the API
and marked as unsupported.

Before Commit c928a05e ("drm/msm/adreno: Move speedbin mapping to
device table"), an unknown speedbin would result in marking all OPPs
as available, but it's better to avoid potentially overclocking the
silicon - the GMU will simply refuse to power up the chip.

Currently, the Adreno speedbin code does just that (AND returns an
invalid error, (int)UINT_MAX). Fix that by defaulting to speedbin 0
(which is conveniently always bound to fuseval == 0).

Fixes: c928a05e ("drm/msm/adreno: Move speedbin mapping to device table")
Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/559604/Signed-off-by: Rob Clark <robdclark@chromium.org>

drivers/gpu/drm/msm/adreno/a6xx_gpu.c

@@ -2730,7 +2730,7 @@ static int a6xx_set_supported_hw(struct device *dev, const struct adreno_info *i
 		DRM_DEV_ERROR(dev,
 			"missing support for speed-bin: %u. Some OPPs may not be supported by hardware\n",
 			speedbin);
-		return UINT_MAX;
+		supp_hw = BIT(0); /* Default */
 	}
 
 	ret = devm_pm_opp_set_supported_hw(dev, &supp_hw, 1);