target/ppc: Remove unused MMU definitions

Remove these confusing and unused definitions.

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20210127232401.3525126-1-f4bug@amsat.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

target/ppc/cpu.h

@@ -2205,9 +2205,6 @@ enum {
  * may be needed for precise access rights control and precise exceptions.
  */
 enum {
-    /* 1 bit to define user level / supervisor access */
-    ACCESS_USER  = 0x00,
-    ACCESS_SUPER = 0x01,
     /* Type of instruction that generated the access */
     ACCESS_CODE  = 0x10, /* Code fetch access                */
     ACCESS_INT   = 0x20, /* Integer load/store access        */