d/patches: renesas: Disable CMD_SPI config option

Currently, the u-boot binary is again going beyond the 1MiB limit on R-Car
Gen3. Upstream u-boot doesn't have this problem as the DISTRO_DEFAULTS
config option is disabled.

Let's disable the CMD_SPI config option to shrink the final image size.

Signed-off-by: Martyn Welch <martyn.welch@collabora.com>