common: command: Fix manual relocation for repeatable command

All platforms which are using MANUAL_RELOC are jumping back to origin
location when repeatable command is called. The reason is that cmd_rep link
is not updated properly. Issue can be reproduced by rewriting origin
U-Boot location through (for example) file download by tftp command.

Fixes: 80a48dd4 ("common: command: Rework the 'cmd is repeatable' logic")
Signed-off-by: Michal Simek <michal.simek@xilinx.com>