drm_hwcomposer: HWC2: Align SetPowerMode Errors with Android VTS

Android VTS tests expect to get Unsupported error for Doze and DozeSuspend
modes and BadParameter for the rest.

Signed-off-by: Vincent Donnefort <vincent.donnefort@arm.com>
diff --git a/drmhwctwo.cpp b/drmhwctwo.cpp
index 9268cdc..b99e122 100644
--- a/drmhwctwo.cpp
+++ b/drmhwctwo.cpp
@@ -763,9 +763,12 @@
     case HWC2::PowerMode::On:
       dpms_value = DRM_MODE_DPMS_ON;
       break;
+    case HWC2::PowerMode::Doze:
+    case HWC2::PowerMode::DozeSuspend:
+      return HWC2::Error::Unsupported;
     default:
       ALOGI("Power mode %d is unsupported\n", mode);
-      return HWC2::Error::Unsupported;
+      return HWC2::Error::BadParameter;
   };
 
   std::unique_ptr<DrmDisplayComposition> composition = compositor_