common: board_f: Use cpu_get_current_dev in print_cpuinfo

Current print_cpuinfo gets the first udevice in CPU class to return
the cpu info. This has problem if the boot CPU is not fixed.

Changing to use new API cpu_get_current_dev to fix the issue.

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