etnaviv: use NORMALIZE_SIGN_EXTEND

etnaviv: use NORMALIZE_SIGN_EXTEND

The blob driver does something like this for all vertex formats:

if (normalize) {
   if (OPENGL_ES30)
      val = VIVS_FE_VERTEX_ELEMENT_CONFIG_NORMALIZE_SIGN_EXTEND;
   else
      val = VIVS_FE_VERTEX_ELEMENT_CONFIG_NORMALIZE_ON;
} else {
   val = VIVS_FE_VERTEX_ELEMENT_CONFIG_NORMALIZE_OFF;
}

As there is no way to get to that information in gallium we always
assume OPENGL_ES30.

Reviewed-by: Jonathan Marek <jonathan@marek.ca>
Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>