cpu: Add DM_FLAG_PRE_RELOC flag to various cpu drivers

It turns out commit c0434407 broke some boards which have DM CPU
driver with CONFIG_DISPLAY_CPUINFO option on. These boards just fail
to boot when print_cpuinfo() is called during boot.

Fixes: c0434407 ("board_f: Use static print_cpuinfo if CONFIG_CPU is active")
Reported-by: Stefan Roese <sr@denx.de>
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Stefan Roese <sr@denx.de>
Tested-by: Stefan Roese <sr@denx.de>