These days modification of the TLB is done in notdirty_mem_write,
so the virtual address and env pointer as unnecessary.

The new name of the function, tlb_unprotect_code, is consistent with
tlb_protect_code.
Reviewed-by: NFam Zheng <famz@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>