rmnet_ctl: remove dependencies

Removes hard dependendencies between rmnet_core and rmnet_ctl.

Change-Id: I9931380fc6406eec5842a824181a0bacbb6ce73a
Acked-by: Weiyi Chen <weiyic@qti.qualcomm.com>
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>