Remove MMU hacks

Unicorn has included some ugly hacks to provide a envirement where vaddr == paddr.
These hacks where to use the full 64 bit mappings on x86 without init the mmu
and some memory redirect for MIPS.

The UC_TLB_CPU mode defaults to vaddr == paddr, therfor these hacks aren't
required anymore.

qemu/target/riscv/cpu.c

@@ -307,7 +307,6 @@ static void riscv_cpu_class_init(struct uc_struct *uc, CPUClass *c, void *data)
     cc->synchronize_from_tb = riscv_cpu_synchronize_from_tb;
     cc->do_unaligned_access = riscv_cpu_do_unaligned_access;
     cc->tcg_initialize = riscv_translate_init;
-    cc->tlb_fill = riscv_cpu_tlb_fill;
     cc->tlb_fill_cpu = riscv_cpu_tlb_fill;
 }