riscv: booti: do not force relocation if force_reloc is not set

If force_reloc flag is not set and booti is called for an address
ouside RAM (i. e. QSPI NOR flash), we should honor that and not try
to force relocation in a bogus fashion.

Signed-off-by: Vitaly Wool <vitaly.wool@konsulko.com>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>