spi: Kconfig: Mark MXS_SPI has DEPRECATED

Mark MXS_SPI as DEPRECATED, this so the resulting build shows
warning for broken configuration enabled and associated code
will remove in v2019.07 release.

Cc: Marek Vasut <marex@denx.de>
Cc: Fabio Estevam <fabio.estevam@nxp.com>
Cc: Michael Trimarchi <michael@amarulasolutions.com>
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
[trini: Switch to DEPRECATED]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index eb32f08..2f494c0 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -383,6 +383,7 @@
 
 config MXS_SPI
 	bool "MXS SPI Driver"
+	depends on DEPRECATED
 	help
 	  Enable the MXS SPI controller driver. This driver can be used
 	  on the i.MX23 and i.MX28 SoCs.