i965: Replace structs with bit-shifting for Gen7 SURFACE_STATE entries.

i965: Replace structs with bit-shifting for Gen7 SURFACE_STATE entries.

Every generation except Gen7 creates SURFACE_STATE entries via a
uint32_t array.  Only Gen7 uses the older bitfield structure, which we
moved away from because it was less efficient.  Convert it for
consistency.

This reduces the compiled size of gen7_wm_surface_state.o by 2.86% in a
release build.

v2: Fix accidental use of BRW_SURFACE_WIDTH/HEIGHT in brw_state_dump.c;
    switch back to gen7_set_surface_mcs_info setting surf[6] directly
    (both per Eric's review comments).

Acked-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Eric Anholt <eric@anholt.net>