spi: make mode visible to both dm and non-dm

spi: make mode visible to both dm and non-dm

Couldn't find the exact reason to define 'mode' for dm,
probably it is not using in non-dm drivers but it need
to visible both dm and non-dm as mode data is getting
dereferred in spi flash core ie common to both.

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