MAINTAINERS: add myself for spi-bcm63xx

I noticed the driver is unclaimed. Since I was the last one doing
substantial work on it, add me as the maintainer.

As it is only found in legacy products, mark it as "Odd Fixes"
instead of "Maintained".

Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>
Acked-by: Florian Fainelli <florian.fainelli@broadcom.com>
Link: https://lore.kernel.org/r/20230708195309.72767-1-jonas.gorski@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: KanjiMonster

MAINTAINERS

@@ -4169,6 +4169,13 @@ F:	Documentation/devicetree/bindings/spi/brcm,bcm63xx-hsspi.yaml
 F:	drivers/spi/spi-bcm63xx-hsspi.c
 F:	drivers/spi/spi-bcmbca-hsspi.c
 
+BROADCOM BCM6348/BCM6358 SPI controller DRIVER
+M:	Jonas Gorski <jonas.gorski@gmail.com>
+L:	linux-spi@vger.kernel.org
+S:	Odd Fixes
+F:	Documentation/devicetree/bindings/spi/spi-bcm63xx.txt
+F:	drivers/spi/spi-bcm63xx.c
+
 BROADCOM ETHERNET PHY DRIVERS
 M:	Florian Fainelli <f.fainelli@gmail.com>
 R:	Broadcom internal kernel review list <bcm-kernel-feedback-list@broadcom.com>