MAINTAINERS: remove myself from sbsa-ref

I am ending my time with Linaro and do not have plans to continue
working on SBSA Reference Platform anymore.

Signed-off-by: Marcin Juszkiewicz <marcin.juszkiewicz@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Leif Lindholm <leif.lindholm@oss.qualcomm.com>
Message-ID: <20241218123055.11220-1-marcin.juszkiewicz@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

MAINTAINERS

@@ -923,7 +923,6 @@ SBSA-REF
 M: Radoslaw Biernacki <rad@semihalf.com>
 M: Peter Maydell <peter.maydell@linaro.org>
 R: Leif Lindholm <leif.lindholm@oss.qualcomm.com>
-R: Marcin Juszkiewicz <marcin.juszkiewicz@linaro.org>
 L: qemu-arm@nongnu.org
 S: Maintained
 F: hw/arm/sbsa-ref.c