defconfig: arm: sdxprairie: Enable rmnet driver

Enable the rmnet module to handle data in the multiplexing and
aggregation protocol (MAP) format.

CRs-Fixed: 2361004
Change-Id: I28507919f66af8e496d0118df7e4c980a8c7c4d1
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>