platform/surface: Disable for RISC-V

platform/surface: Disable for RISC-V

With CONFIG_ACPI enabled for RISC-V, this driver gets enabled
in allmodconfig build. However, RISC-V doesn't support sub-word
atomics which is used by this driver and hence allmodconfig
build will fail.

There is currently no plan to support this driver for RISC-V. So,
disable this driver for RISC-V even when ACPI is enabled.

Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Acked-by: Maximilian Luz <luzmaximilian@gmail.com>
Link: https://lore.kernel.org/r/20230515054928.2079268-3-sunilvl@ventanamicro.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>