riscv: fix typo in init.c

Commit 01062356 introduced a typo in "__initdata" spelling
which led to build breakage for XIP. Fix that.

Fixes: 01062356

 ("riscv: mm: init: Consolidate vars, functions")
Signed-off-by: Vitaly Wool <vitaly.wool@konsulko.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>