anv: Work around ANGLE being sloppy with buffer view valid usage.
Fixes an assertion failure in KHR-GLES31.core.texture_buffer.texture_buffer_texture_buffer_range when a storage+uniform buffer gets an RGB32F buffer view created against it.
Fixes an assertion failure in KHR-GLES31.core.texture_buffer.texture_buffer_texture_buffer_range when a storage+uniform buffer gets an RGB32F buffer view created against it.