drivers: rmnet_shs: Remove netdev dereference

Previously there was a dereference of RPS CPU
when updating flows in rmnet_shs_wq. After changing
logic to handle change of RPS mask net_rx is responsible
for catching changes in a flow's CPU. This leaves this
dereference unessesary.

This change removes that dereference and relies on the
trustworthy saved CPU of the flow.

<6> Unable to handle kernel NULL pointer dereference at virtual address 00000000
<6> Mem abort info:
<6>   Exception class = DABT (current EL), IL = 32 bits
<6>   SET = 0, FnV = 0
<6>   EA = 0, S1PTW = 0
<6>   FSC = 6
<6> Data abort info:
<6>   ISV = 0, ISS = 0x00000006
<6>   CM = 0, WnR = 0
<6> user pgtable: 4k pages, 39-bit VAs, pgd = 0000000019917200
<6> [0000000000000000] *pgd=0000000000000000, *pud=0000000000000000
<6> Internal error: Oops: 96000006 [#1] PREEMPT SMP
<2> pc : rmnet_shs_wq_update_cpu_rx_tbl+0x44/0x224 [rmnet_shs]
<2> lr : rmnet_shs_wq_update_cpu_rx_tbl+0x3c/0x224 [rmnet_shs]
<2> Call trace:
<2>  rmnet_shs_wq_update_cpu_rx_tbl+0x44/0x224 [rmnet_shs]
<2>  rmnet_shs_wq_process_wq+0x184/0x83c [rmnet_shs]
<2>  process_one_work+0x1e0/0x410
<2>  worker_thread+0x27c/0x38c
<2>  kthread+0x12c/0x13c
<2>  ret_from_fork+0x10/0x18
<6> Code: f9401274 94000ed6 f9400a88 f9419508 (f9400108)

Change-Id: Id50a7da2cccccacf4694a1bb43d62ec28e2b4462
Acked-by: Raul Martinez <mraul@qti.qualcomm.com>
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>