gpu: ipu-v3: Kconfig: Remove SOC_IMX6SL from IMX_IPUV3_CORE Kconfig

SOC_IMX6SL does not have the IPU block, so remove it from the Kconfig entry.
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

drivers/gpu/ipu-v3/Kconfig

 config IMX_IPUV3_CORE
 	tristate "IPUv3 core support"
-	depends on SOC_IMX5 || SOC_IMX6Q || SOC_IMX6SL || ARCH_MULTIPLATFORM
+	depends on SOC_IMX5 || SOC_IMX6Q || ARCH_MULTIPLATFORM
 	depends on RESET_CONTROLLER
 	select GENERIC_IRQ_CHIP
 	help