sunxi: add missing CONFIG_VIDEO_SUN4I_CSI Kconfig symbol

Simply disable this for now, if anyone wants to use CSI feel free to
package it as a kernel module package.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

target/linux/sunxi/config-5.10

@@ -498,6 +498,7 @@ CONFIG_VFPv3=y
 CONFIG_VHOST=y
 CONFIG_VHOST_IOTLB=y
 CONFIG_VHOST_NET=y
+# CONFIG_VIDEO_SUN4I_CSI is not set
 CONFIG_VM_EVENT_COUNTERS=y
 CONFIG_VT=y
 CONFIG_VT_CONSOLE=y