target/mips: Explicit Release 6 MMU types

As of Release 6, MMU type 4 is assigned to "Dual Variable-Page-Size
and Fixed-Page-Size TLBs" and type 2 to "Block Address Translation.

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20201201132817.2863301-4-f4bug@amsat.org>

target/mips/internal.h

@@ -16,10 +16,11 @@
  * CP0C0_MT field.
  */
 enum mips_mmu_types {
-    MMU_TYPE_NONE,
-    MMU_TYPE_R4000,
-    MMU_TYPE_RESERVED,
-    MMU_TYPE_FMT,
+    MMU_TYPE_NONE       = 0,
+    MMU_TYPE_R4000      = 1,    /* Standard TLB */
+    MMU_TYPE_BAT        = 2,    /* Block Address Translation */
+    MMU_TYPE_FMT        = 3,    /* Fixed Mapping */
+    MMU_TYPE_DVF        = 4,    /* Dual VTLB and FTLB */
     MMU_TYPE_R3000,
     MMU_TYPE_R6000,
     MMU_TYPE_R8000