wcn36xx: Remove warning message when dev is NULL for arm64 dma_alloc.

wcn36xx: Remove warning message when dev is NULL for arm64 dma_alloc.

arm64 has requirement that all the dma operations have actual device.
Otherwise, following warnning message shown and dma allocation fails:

WARNING: CPU: 0 PID: 954 at arch/arm64/mm/dma-mapping.c:106 __dma_alloc+0x24c/0x258()
Use an actual device structure for DMA allocation
Modules linked in: wcn36xx wcn36xx_platform
CPU: 0 PID: 954 Comm: ifconfig Not tainted 4.0.0+ #14
Hardware name: Qualcomm Technologies, Inc. MSM 8916 MTP (DT)
Call trace:
[<ffffffc000089904>] dump_backtrace+0x0/0x124
[<ffffffc000089a38>] show_stack+0x10/0x1c
[<ffffffc000627114>] dump_stack+0x80/0xc4
[<ffffffc0000b2e64>] warn_slowpath_common+0x98/0xd0
[<ffffffc0000b2ee8>] warn_slowpath_fmt+0x4c/0x58
[<ffffffc00009487c>] __dma_alloc+0x248/0x258
[<ffffffbffc009270>] wcn36xx_dxe_allocate_mem_pools+0xc4/0x108 [wcn36xx]
[<ffffffbffc0079c4>] wcn36xx_start+0x38/0x240 [wcn36xx]
[<ffffffc0005f161c>] ieee80211_do_open+0x1b0/0x9a4
[<ffffffc0005f1e68>] ieee80211_open+0x58/0x68
[<ffffffc00051693c>] __dev_open+0xb0/0x120
[<ffffffc000516c10>] __dev_change_flags+0x88/0x150
[<ffffffc000516cf4>] dev_change_flags+0x1c/0x5c
[<ffffffc000570950>] devinet_ioctl+0x644/0x6f0

Signed-off-by: Yin, Fengwei <fengwei.yin@linaro.org>
Acked-by: Bjorn Andersson <bjorn.andersson@sonymobile.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>