nak: Turing starts at SM73

The low-end Turing cards (TU117 for sure) are SM73, not SM75.  These are
the cards on which we have tensor cores but they're so slow as to be
almost useless.  We're not back-porting this because nouveau currently
returns 75 for these cards and because Volta binaries work fine on
Turing so they'll just be a little slower.  We have, however, seen this
advertised by NVRM so we want our handling of shader models to be
correct.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/34201>

src/nouveau/compiler/nak/sm70.rs

@@ -22,7 +22,7 @@ impl ShaderModel70 {
     }
 
     fn has_uniform_alu(&self) -> bool {
-        self.sm >= 75
+        self.sm >= 73
     }
 }
 
@@ -161,7 +161,7 @@ impl SM70Encoder<'_> {
     }
 
     fn set_ureg(&mut self, range: Range<usize>, reg: RegRef) {
-        assert!(self.sm.sm >= 75);
+        assert!(self.sm.sm >= 73);
         assert!(range.len() == 8);
         assert!(reg.file() == RegFile::UGPR);
         assert!(reg.base_idx() <= 63);

src/nouveau/compiler/nak/sph.rs

@@ -110,7 +110,7 @@ impl ShaderProgramHeader {
             SPHV3_T1_SPH_TYPE_TYPE_01_VTG
         };
 
-        let sph_version = if sm >= 75 { 4 } else { 3 };
+        let sph_version = if sm >= 73 { 4 } else { 3 };
         res.set_sph_type(sph_type, sph_version);
         res.set_shader_type(shader_type);
 

src/nouveau/compiler/nak_nir.c

@@ -1073,7 +1073,7 @@ nak_postprocess_nir(nir_shader *nir,
 
    bool lcssa_progress = nir_convert_to_lcssa(nir, false, false);
 
-   if (nak->sm >= 75) {
+   if (nak->sm >= 73) {
       if (lcssa_progress) {
          OPT(nir, nak_nir_mark_lcssa_invariants);
       }

src/nouveau/compiler/nak_nir_algebraic.py

@@ -30,7 +30,7 @@ c = 'c'
 s = 's'
 
 # common conditions to improve readability
-volta = 'nak->sm >= 70 && nak->sm < 75'
+volta = 'nak->sm >= 70 && nak->sm < 73'
 
 algebraic_lowering = [
     # Volta doesn't have `IMNMX`