device_add() expects that any memory allocated via devm_* API is only
done in the device's probe function.

Fix below boot warning:
[    3.092348] WARNING: at drivers/base/dd.c:286
[    3.096637] Modules linked in:
[    3.099697] CPU: 0 PID: 25 Comm: kworker/u2:1 Tainted: G W 3.16.1-s3k-drv-999-svn5771_knld-999 #158
[ 3.109610] Workqueue: deferwq deferred_probe_work_func
[    3.114736] task: c787f020 ti: c790c000 task.ti: c790c000
[    3.120062] NIP: c01df158 LR: c01df144 CTR: 00000000
[    3.124983] REGS: c790db30 TRAP: 0700   Tainted: G        W (3.16.1-s3k-drv-999-svn5771_knld-999)
[    3.134162] MSR: 00029032 <EE,ME,IR,DR,RI>  CR: 22002082 XER: 20000000
[    3.140703]
[    3.140703] GPR00: 00000001 c790dbe0 c787f020 00000044 00000054 00000308 c056da0e 20737069
[    3.140703] GPR08: 33323736 000ebfe0 00000308 000ebfdf 22002082 00000000 c046c5a0 c046c608
[    3.140703] GPR16: c046c614 c046c620 c046c62c c046c638 c046c648 c046c654 c046c68c c046c6c4
[    3.140703] GPR24: 00000000 00000000 00000003 c0401aa0 c0596638 c059662c c054e7a8 c7996800
[    3.170102] NIP [c01df158] driver_probe_device+0xf8/0x334
[    3.175431] LR [c01df144] driver_probe_device+0xe4/0x334
[    3.180633] Call Trace:
[    3.183093] [c790dbe0] [c01df144] driver_probe_device+0xe4/0x334 (unreliable)
[    3.190147] [c790dc10] [c01dd15c] bus_for_each_drv+0x7c/0xc0
[    3.195741] [c790dc40] [c01df5fc] device_attach+0xcc/0xf8
[    3.201076] [c790dc60] [c01dd6d4] bus_probe_device+0xb4/0xc4
[    3.206666] [c790dc80] [c01db9f8] device_add+0x270/0x564
[    3.211923] [c790dcc0] [c0219e84] spi_add_device+0xc0/0x190
[    3.217427] [c790dce0] [c021a79c] spi_register_master+0x720/0x834
[    3.223455] [c790dd40] [c021cb48] of_fsl_spi_probe+0x55c/0x614
[    3.229234] [c790dda0] [c01e0d2c] platform_drv_probe+0x30/0x74
[    3.234987] [c790ddb0] [c01df18c] driver_probe_device+0x12c/0x334
[    3.241008] [c790dde0] [c01dd15c] bus_for_each_drv+0x7c/0xc0
[    3.246602] [c790de10] [c01df5fc] device_attach+0xcc/0xf8
[    3.251937] [c790de30] [c01dd6d4] bus_probe_device+0xb4/0xc4
[    3.257536] [c790de50] [c01de9d8] deferred_probe_work_func+0x98/0xe0
[    3.263816] [c790de70] [c00305b8] process_one_work+0x18c/0x440
[    3.269577] [c790dea0] [c0030a00] worker_thread+0x194/0x67c
[    3.275105] [c790def0] [c0039198] kthread+0xd0/0xe4
[    3.279911] [c790df40] [c000c6d0] ret_from_kernel_thread+0x5c/0x64
[    3.285970] Instruction dump:
[    3.288900] 80de0000 419e01d0 3b7b0038 3c60c046 7f65db78 38635264 48211b99 813f00a0
[    3.296559] 381f00a0 7d290278 3169ffff 7c0b4910 <0f000000> 93df0044 7fe3fb78 4bfffd4d

Reported-by: leroy christophe <christophe.leroy@c-s.fr>
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Tested-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org