MAINTAINERS: Add maintainer of DW APB SSI driver

Add myself as a maintainer of the Synopsis DesignWare APB SSI driver.

Suggested-by: Andy Shevchenko <[e-mail]>
Signed-off-by: Serge Semin <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

MAINTAINERS

···
 F:	Documentation/devicetree/bindings/gpio/snps,dw-apb-gpio.yaml
 F:	drivers/gpio/gpio-dwapb.c
 
+SYNOPSYS DESIGNWARE APB SSI DRIVER
+M:	Serge Semin <[e-mail]>
+L:	[e-mail]
+S:	Supported
+F:	Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.yaml
+F:	drivers/spi/spi-dw*
+
 SYNOPSYS DESIGNWARE AXI DMAC DRIVER
 M:	Eugeniy Paltsev <[e-mail]>
 S:	Maintained