blackberry: Change path for BBNDKs

Put them under /opt and also rename the folder as bbndks, so they
don't get confused with the Android ndk.

Change-Id: Ie2ee4aec17c93faf61a3a7181f3d7d74db03ae9d
Reviewed-by: Wolfgang Bremer <wbremer@blackberry.com>
Reviewed-by: Sergio Ahumada <sahumada@blackberry.com>