net: qualcomm: rmnet: Remove invalid device free

An incorrect additional free of the netdevice outside of the
dellink framework caused the following call stack to be printed.
Fix by removing this call.

[  362.230708] kernel BUG at kernel/msm-4.14/net/core/dev.c:8198!
[  362.248270] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
[  362.288484] CPU: 4 PID: 755 Comm: POSIX timer 0 Tainted: G S
W  O    4.14.43+ #1
[  362.303838] task: ffffffc746b23380 task.stack: ffffff801cff0000
[  362.309923] pc : free_netdev+0x108/0x110
[  362.313951] lr : free_netdev+0x74/0x110

CRs-Fixed: 2254860
Change-Id: I70125608a699e2ef89c646c55c0aeeca1f5cc1fe
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>