nak: make ipa encoding match the order in codegen gv100

78 has interp mode
76 has sample mode

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24998>

src/nouveau/compiler/nak_encode_sm75.rs

@@ -1437,20 +1437,20 @@ impl SM75Instr {
 
         self.set_field(
             76..78,
-            match op.freq {
-                InterpFreq::Pass => 0_u8,
-                InterpFreq::Constant => 1_u8,
-                InterpFreq::State => 2_u8,
-            },
-        );
-        self.set_field(
-            78..80,
             match op.loc {
                 InterpLoc::Default => 0_u8,
                 InterpLoc::Centroid => 1_u8,
                 InterpLoc::Offset => 2_u8,
             },
         );
+        self.set_field(
+            78..80,
+            match op.freq {
+                InterpFreq::Pass => 0_u8,
+                InterpFreq::Constant => 1_u8,
+                InterpFreq::State => 2_u8,
+            },
+        );
 
         self.set_reg_src(32..40, op.offset);