spi: bcm63xx-spi: allow building for BMIPS

bcm63xx-spi controller is present on several BMIPS SoCs (BCM6358, BCM6362,
BCM6368 and BCM63268).
Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20200615090943.2936839-3-noltari@gmail.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/Kconfig

@@ -149,7 +149,7 @@ config SPI_BCM2835AUX
 
 config SPI_BCM63XX
 	tristate "Broadcom BCM63xx SPI controller"
-	depends on BCM63XX || COMPILE_TEST
+	depends on BCM63XX || BMIPS_GENERIC || COMPILE_TEST
 	help
 	  Enable support for the SPI controller on the Broadcom BCM63xx SoCs.