xtensa: remove ZSR_MMU_0 and ZSR_MMU_1

They are not being used in the code so there is no need to
reserve them as scratch registers.

Signed-off-by: Daniel Leung <[email protected]>

Author: dcpleung

arch/xtensa/core/gen_zsr.py

@@ -31,7 +31,7 @@ def parse_args():
 
 NEEDED = ["A0SAVE", "CPU"]
 if args.mmu:
-    NEEDED += ["MMU_0", "MMU_1", "DBLEXC"]
+    NEEDED += ["DBLEXC"]
 if args.coherence:
     NEEDED += ["FLUSH"]