net: mhi-ep: use netif_rx() instead of __netif_rx()

The function mhi_ep_net_ul_callback() is called from the worker, so the
generic netif_rx() should be used instead of __netif_rx().

This fixes the following warning:

WARNING: CPU: 0 PID: 97 at net/core/dev.c:4889 __netif_rx+0x3c/0x70
Modules linked in:
CPU: 0 PID: 97 Comm: kworker/0:2 Tainted: G S                5.18.0-rc2-00343-g4bf6939c60f4-dirty #866
Workqueue: mhi_ep_wq mhi_ep_ch_ring_worker
pstate: 62400005 (nZCv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : __netif_rx+0x3c/0x70
lr : mhi_ep_net_ul_callback+0xc4/0x230
sp : ffff80000937bc60
x29: ffff80000937bc60 x28: ffff2476905c2880 x27: ffff2476905c2890
x26: ffff247689d3a400 x25: 0000000000000054 x24: 0000000000007fac
x23: fffffbffeff1af00 x22: ffff247689177700 x21: ffff80000937bd50
x20: ffff247680f21b40 x19: ffff247684f35900 x18: 0000000000000000
x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000
x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000
x11: 0000000000000000 x10: 0000000000000000 x9 : 255f98230000c501
x8 : 7d7b00000201a8c0 x7 : 0101a8c0264f0140 x6 : 000000000000fec0
x5 : ffff2476905b0094 x4 : 00000000000000a8 x3 : ffff247684f35900
x2 : 0000000000000094 x1 : 0000000000000000 x0 : 0000000000000000
Call trace:
 __netif_rx+0x3c/0x70
 mhi_ep_net_ul_callback+0xc4/0x230
 mhi_ep_ch_ring_worker+0x260/0x480
 process_one_work+0x288/0x660
 worker_thread+0x74/0x450
 kthread+0xfc/0x100
 ret_from_fork+0x10/0x20
irq event stamp: 2134
hardirqs last  enabled at (2133): [<ffffd8e36072a3a8>] kmalloc_large_node+0xd8/0x110
hardirqs last disabled at (2134): [<ffffd8e3614d4058>] el1_dbg+0x24/0x8c
softirqs last  enabled at (2122): [<ffffd8e360490410>] _stext+0x410/0x588
softirqs last disabled at (2113): [<ffffd8e36051d328>] __irq_exit_rcu+0x158/0x174

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>