drm_hwcomposer: avoid using signed errno on uint32 type

DrmGenericImporter::ConvertHalFormatToDrm() should not return negative values.

 - Use DRM_FORMAT_INVALID instead of -EINVAL
 - Check DrmGenericImporter::ConvertHalFormatToDrm() result value in
   DrmGenericImporter::ImportBuffer()

Signed-off-by: Roman Stratiienko <roman.stratiienko@globallogic.com>
diff --git a/platform/platformdrmgeneric.cpp b/platform/platformdrmgeneric.cpp
index 9ac601f..f8a1858 100644
--- a/platform/platformdrmgeneric.cpp
+++ b/platform/platformdrmgeneric.cpp
@@ -89,7 +89,7 @@
       return DRM_FORMAT_YVU420;
     default:
       ALOGE("Cannot convert hal format to drm format %u", hal_format);
-      return -EINVAL;
+      return DRM_FORMAT_INVALID;
   }
 }
 
@@ -128,6 +128,8 @@
   bo->height = gr_handle->height;
   bo->hal_format = gr_handle->format;
   bo->format = ConvertHalFormatToDrm(gr_handle->format);
+  if (bo->format == DRM_FORMAT_INVALID)
+    return -EINVAL;
   bo->usage = gr_handle->usage;
   bo->pixel_stride = (gr_handle->stride * 8) /
                      DrmFormatToBitsPerPixel(bo->format);
diff --git a/platform/platformhisi.cpp b/platform/platformhisi.cpp
index 64b410b..874a31c 100644
--- a/platform/platformhisi.cpp
+++ b/platform/platformhisi.cpp
@@ -121,9 +121,9 @@
     return ret;
   }
 
-  int32_t fmt = ConvertHalFormatToDrm(hnd->req_format);
-  if (fmt < 0)
-    return fmt;
+  uint32_t fmt = ConvertHalFormatToDrm(hnd->req_format);
+  if (fmt == DRM_FORMAT_INVALID)
+    return -EINVAL;
 
   is_rgb = IsDrmFormatRgb(fmt);
   modifiers[0] = ConvertGrallocFormatToDrmModifiers(hnd->internal_format,
diff --git a/platform/platformmeson.cpp b/platform/platformmeson.cpp
index 7bde5cd..10c2745 100644
--- a/platform/platformmeson.cpp
+++ b/platform/platformmeson.cpp
@@ -98,9 +98,9 @@
     return ret;
   }
 
-  int32_t fmt = ConvertHalFormatToDrm(hnd->req_format);
-  if (fmt < 0)
-    return fmt;
+  uint32_t fmt = ConvertHalFormatToDrm(hnd->req_format);
+  if (fmt == DRM_FORMAT_INVALID)
+    return -EINVAL;
 
   modifiers[0] = ConvertGrallocFormatToDrmModifiers(hnd->internal_format);