ARM: rmobile: Convert M2N Gose to DM_SPI{,_FLASH}

Enable DM_SPI and DM_SPI_FLASH in U-Boot on M2N Gose.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>