Return empty modifier list if format is not supported on a plane

The plane may not support the specific format for scanout. This is fine
if the buffers have an opaque version (ie: XRGB and ARGB) and blending
is disabled for scanout as the opaque version is used for scanout.

BUG=1082545
TEST=Ran in cros VM

Change-Id: I1a5caac796999d778eea272eed06dcbc261ac5e4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2212980
Commit-Queue: Daniel Nicoara <dnicoara@chromium.org>
Reviewed-by: Daniele Castagna <dcastagna@chromium.org>
Cr-Commit-Position: refs/heads/master@{#771807}

ui/ozone/platform/drm/gpu/hardware_display_plane.cc

@@ -126,11 +126,12 @@ std::vector<uint64_t> HardwareDisplayPlane::ModifiersForFormat(
     uint32_t format) const {
   std::vector<uint64_t> modifiers;
 
-  uint32_t format_index =
-      std::find(supported_formats_.begin(), supported_formats_.end(), format) -
-      supported_formats_.begin();
-  DCHECK_LT(format_index, supported_formats_.size());
+  auto it =
+      std::find(supported_formats_.begin(), supported_formats_.end(), format);
+  if (it == supported_formats_.end())
+    return modifiers;
 
+  uint32_t format_index = it - supported_formats_.begin();
   for (const auto& modifier : supported_format_modifiers_) {
     // modifier.formats is a bitmask of the formats the modifier
     // applies to, starting at format modifier.offset. That is, if bit