cx25821: Add driver to the building system

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/staging/Kconfig b/drivers/staging/Kconfig
index 10d3fcf..82b3489 100644
--- a/drivers/staging/Kconfig
+++ b/drivers/staging/Kconfig
@@ -47,6 +47,8 @@
 
 source "drivers/staging/go7007/Kconfig"
 
+source "drivers/staging/cx25821/Kconfig"
+
 source "drivers/staging/usbip/Kconfig"
 
 source "drivers/staging/winbond/Kconfig"