[PATCH v3 1/4] frv: io: Accept const void pointers for read{b,w,l}()

The frv port uses compiler builtins, __builtin_read*(), for the I/O read routines. Unfortunately, these don't accept const void pointers although the generic ASM implementations do, so generic code passing const pointers to these APIs cause compilers to emit warnings. Add wrapper functions that

[PATCH v3 1/4] frv: io: Accept const void pointers for read{b,w,l}()

The frv port uses compiler builtins, __builtin_read*(), for the I/O read routines. Unfortunately, these don't accept const void pointers although the generic ASM implementations do, so generic code passing const pointers to these APIs cause compilers to emit warnings. Add wrapper functions that