i965/sf: Drop unnecessary push/pop in do_twoside_color.
i965/sf: Drop unnecessary push/pop in do_twoside_color.

None of the assembly emitters called between push and pop actually
change the state.  So, we can drop these.

Signed-off-by: Kenneth Graunke <bd2562f754ec92342f93f61c25d731e290a2ffa8@whitecape.org>
Reviewed-by: Matt Turner <789b315743a28dd066a4ba1459c35951c291d8a6@gmail.com>

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