i965/fs: add support for shader float control to remove_extra_rounding_modes()

i965/fs: add support for shader float control to remove_extra_rounding_modes()

The remove_extra_rounding_modes() optimization will remove duplicated
rounding mode changes.

v2:
- Fix bug in the rounding mode change (Alejandro).

v3:
- Fix rounding modes.

v4:
- Updated to renamed shader info member and enum values (Andres).

v5:
- Simplify flags logic operations (Caio).

Signed-off-by: Samuel Iglesias Gonsálvez <siglesias@igalia.com>
Signed-off-by: Andres Gomez <agomez@igalia.com>
Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com>