sf: probe: Code cleanup

- Move bar read code below the bar write hance both
  at once place, hence it easy for #ifdef macro only
  once and readable.
- Move read_cmd_array at top

Tested-by: Jagan Teki <jteki@openedev.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Jagan Teki <jteki@openedev.com>