arm64 :show_regs: show the address before relocation

After relocation, when error happends, it is hard to track
ELR and LR with asm file objdumped from elf file.

So subtract the gd->reloc_off the reflect the compliation address.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Simon Glass <sjg@chromium.org>