spi: ca_sflash: Remove redundant dependency

This is inside of an 'if DM_SPI' block, and thus always true.

Signed-off-by: Alexander Dahl <ada@thorsis.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 96ea033..6555142 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -135,7 +135,7 @@
 
 config CORTINA_SFLASH
 	bool "Cortina-Access Serial Flash controller driver"
-	depends on DM_SPI && SPI_MEM
+	depends on SPI_MEM
 	help
 	  Enable the Cortina-Access Serial Flash controller driver. This driver
 	  can be used to access the SPI NOR/NAND flash on platforms embedding this