defconfig: sdm855: Enable rmnet_data

Enable the rmnet_data driver for processing multiplexing and
aggregation protocol packets from hardware.

CRs-Fixed: 2086060
Change-Id: I89ad3c6f24bc243e912b3214998b77864f104ad3
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>