i965: Do not store SRC after 0 on component control.

i965: Do not store SRC after 0 on component control.

The PRM SKL-Vol 2b-05.16 says:

   "Within a VERTEX_ELEMENT_STATE structure, if a Component Control
   field is set to something other than VFCOMP_STORE_SRC, no
   higher-numbered Component Control fields may be set to
   VFCOMP_STORE_SRC. In other words, only trailing components can be set
   to something other than VFCOMP_STORE_SRC."

Since we set the component 1 to VFCOMP_STORE_0 on gen8+, and
VFCOMP_STORE_IID on gen5+, and we are not using components 2 and 3,
let's also set them to VFCOMP_STORE_0.

Signed-off-by: Rafael Antognolli <rafael.antognolli@intel.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Anuj Phogat <anuj.phogat@gmail.com>