spi: rpc-if: Add missing MODULE_DEVICE_TABLE

Add missing MODULE_DEVICE_TABLE definition for automatic loading of the
driver when it is built as a module.

Fixes: eb8d6d46 ("spi: add Renesas RPC-IF driver")
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://patch.msgid.link/20240731072955.224125-1-biju.das.jz@bp.renesas.com


Signed-off-by: Mark Brown <broonie@kernel.org>