net: qualcomm: rmnet: Fix leak in device creation failure

If the rmnet device creation fails in the newlink either while
registering with the physical device or after subsequent
operations, the rmnet endpoint information is never freed.

Fixes: ceed73a2 ("drivers: net: ethernet: qualcomm: rmnet: Initial implementation")
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>
Signed-off-by: David S. Miller <davem@davemloft.net>