cutelyst: fix kconfig syntax

Commit cb3c56e35 (cutelyst: Add dependency on Kernel headers >= 3.3) used
invalid kconfig syntax, breaking menuconfig:

make menuconfig
package/cutelyst/Config.in:19: syntax error
package/cutelyst/Config.in:18: invalid option
Makefile:900: recipe for target 'menuconfig' failed

Fix it by using 'depends ON' instead.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/cutelyst/Config.in

@@ -15,4 +15,4 @@ config BR2_PACKAGE_CUTELYST
 comment "cutelyst needs a toolchain w/ C++, gcc >= 4.8, headers >= 3.3"
 	depends on BR2_PACKAGE_QT5
 	depends on !BR2_INSTALL_LIBSTDCPP || !BR2_TOOLCHAIN_GCC_AT_LEAST_4_8
-	depends !BR2_TOOLCHAIN_HEADERS_AT_LEAST_3_3
+	depends on !BR2_TOOLCHAIN_HEADERS_AT_LEAST_3_3