grantlee: Disable on non-supported platforms

This package selects BR2_PACKAGE_QT_SCRIPT which is not supported on
certain platforms. To prevent this behaviour we use the same solution as
we applied for BR2_PACKAGE_QT_SCRIPT

Signed-off-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>