sh: ecovec24: Make SPI mode explicit

Commit cf9e4784 ("spi: sh-msiof: Add slave mode support") added
a new mode member to the sh_msiof_spi_info structure, but did not update
any board files.  Hence all users in board files rely on the default
being host mode.

Make this unambiguous by configuring host mode explicitly.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Signed-off-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>