scsi: scsi_dh_alua: Fix memleak for 'qdata' in alua_activate()

In the Linux kernel, the following vulnerability has been resolved:

scsi: scsi_dh_alua: Fix memleak for 'qdata' in alua_activate()

If alua_rtpg_queue() failed from alua_activate(), then 'qdata' is not

freed, which will cause following memleak:

unreferenced object 0xffff88810b2c6980 (size 32):

comm "kworker/u16:2", pid 635322, jiffies 4355801099 (age 1216426.076s)

hex dump (first 32 bytes):

00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................

40 39 24 c1 ff ff ff ff 00 f8 ea 0a 81 88 ff ff @9$.............

backtrace:

[<0000000098f3a26d>] alua_activate+0xb0/0x320

[<000000003b529641>] scsi_dh_activate+0xb2/0x140

[<000000007b296db3>] activate_path_work+0xc6/0xe0 [dm_multipath]

[<000000007adc9ace>] process_one_work+0x3c5/0x730

[<00000000c457a985>] worker_thread+0x93/0x650

[<00000000cb80e628>] kthread+0x1ba/0x210

[<00000000a1e61077>] ret_from_fork+0x22/0x30

Fix the problem by freeing 'qdata' in error path.