rmnet: shs: Fix uninitialized use in init

If the physical device is not in up state before a virtual device
is brought up, there is an use of uninitialized variable leading to
the following-

145.153137:   <6> Unable to handle kernel NULL pointer dereference at virtual address 0000000000000018
145.153156:   <6> Mem abort info:
145.153165:   <6>   ESR = 0x96000005
145.153176:   <6>   Exception class = DABT (current EL), IL = 32 bits
145.153186:   <6>   SET = 0, FnV = 0
145.153195:   <6>   EA = 0, S1PTW = 0
145.153203:   <6> Data abort info:
145.153212:   <6>   ISV = 0, ISS = 0x00000005
145.153221:   <6>   CM = 0, WnR = 0
145.153237:   <6> user pgtable: 4k pages, 39-bit VAs, pgdp = 000000007f1dc94f
145.153246:   <6> [0000000000000018] pgd=0000000000000000, pud=0000000000000000
145.153269:   <6> Internal error: Oops: 96000005 [#1] PREEMPT SMP
145.153524:   <2> pc : rmnet_get_endpoint+0x4/0x48
145.153607:   <2> lr : rmnet_shs_wq_gather_rmnet_ep+0x68/0x1f0 [rmnet_shs]
145.155341:   <2> Call trace:
145.155359:   <2>  rmnet_get_endpoint+0x4/0x48
145.155395:   <2>  rmnet_shs_wq_init+0x168/0x328 [rmnet_shs]
145.155428:   <2>  rmnet_shs_dev_notify_cb+0x234/0x388 [rmnet_shs]
145.155450:   <2>  raw_notifier_call_chain+0x3c/0x68
145.155472:   <2>  __dev_notify_flags+0xa0/0x190
145.155486:   <2>  dev_change_flags+0x48/0x60
145.155506:   <2>  devinet_ioctl+0x3a8/0x658
145.155523:   <2>  inet_ioctl+0xb4/0x280
145.155541:   <2>  sock_do_ioctl+0x44/0x230
145.155554:   <2>  sock_ioctl+0x25c/0x3d8
145.155575:   <2>  do_vfs_ioctl+0x5dc/0x928
145.155589:   <2>  __arm64_sys_ioctl+0x70/0x98
145.155608:   <2>  el0_svc_common+0xa0/0x158
145.155623:   <2>  el0_svc_handler+0x6c/0x88
145.155640:   <2>  el0_svc+0x8/0xc

CRs-Fixed: 2527900
Change-Id: Iece4e21c5acc5504fb3939f489d221a1e949b31a
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>