drm: remove `const` attribute to hint at caller that they now own the memory

Signed-off-by: Eric Engestrom <eric.engestrom@imgtec.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/include/drm/drm_fourcc.h b/include/drm/drm_fourcc.h
index 030d22d..b106337 100644
--- a/include/drm/drm_fourcc.h
+++ b/include/drm/drm_fourcc.h
@@ -32,6 +32,6 @@
 int drm_format_vert_chroma_subsampling(uint32_t format);
 int drm_format_plane_width(int width, uint32_t format, int plane);
 int drm_format_plane_height(int height, uint32_t format, int plane);
-const char *drm_get_format_name(uint32_t format) __malloc;
+char *drm_get_format_name(uint32_t format) __malloc;
 
 #endif /* __DRM_FOURCC_H__ */