MAINTAINERS: add tambarus as R for Samsung SPI

I'm currently working on a Samsung SoC which includes SPI.
I'd like to be Cc'ed to further contributions and help on reviewing
them. Add me as reviewer.

Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Acked-by: Andi Shyti <andi.shyti@kernel.org>
Reviewed-by: Sam Protsenko <semen.protsenko@linaro.org>
Link: https://patch.msgid.link/20250213-gs101-spi-r-v1-1-1e3ab8096873@linaro.org


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