intel/blorp: Fix a hang caused by invalid dispatch enables on gfx7

intel/blorp: Fix a hang caused by invalid dispatch enables on gfx7

Because commit b9403b1c477 moved dispatch enable handling away from the
compiler, the drivers must ensure correct dispatch enable values. This
is handled by the intel_set_ps_dispatch_state function.

v2: Fix gfx6 build and use brw_fs_get_dispatch_enables for gfx6 in
crocus
v3: Rebase, use intel_set_ps_dispatch_state, drop gfx6 handling

Fixes: b9403b1c477 ("intel: factor out dispatch PS enabling logic")
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/20267>