riscv: fix misalgned trap vector base address

The trap vector marked by label .Lsecondary_park must align on a
4-byte boundary, as the {m,s}tvec is defined to require 4-byte
alignment.

Signed-off-by: Chen Lu <181250012@smail.nju.edu.cn>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
Fixes: e011995e ("RISC-V: Move relocate and few other functions out of __init")
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>