thermal: int340x: fix memory leak in int3400_notify()

It is easy to hit the below memory leaks in my TigerLake platform:

unreferenced object 0xffff927c8b91dbc0 (size 32):
  comm "kworker/0:2", pid 112, jiffies 4294893323 (age 83.604s)
  hex dump (first 32 bytes):
    4e 41 4d 45 3d 49 4e 54 33 34 30 30 20 54 68 65  NAME=INT3400 The
    72 6d 61 6c 00 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b a5  rmal.kkkkkkkkkk.
  backtrace:
    [<ffffffff9c502c3e>] __kmalloc_track_caller+0x2fe/0x4a0
    [<ffffffff9c7b7c15>] kvasprintf+0x65/0xd0
    [<ffffffff9c7b7d6e>] kasprintf+0x4e/0x70
    [<ffffffffc04cb662>] int3400_notify+0x82/0x120 [int3400_thermal]
    [<ffffffff9c8b7358>] acpi_ev_notify_dispatch+0x54/0x71
    [<ffffffff9c88f1a7>] acpi_os_execute_deferred+0x17/0x30
    [<ffffffff9c2c2c0a>] process_one_work+0x21a/0x3f0
    [<ffffffff9c2c2e2a>] worker_thread+0x4a/0x3b0
    [<ffffffff9c2cb4dd>] kthread+0xfd/0x130
    [<ffffffff9c201c1f>] ret_from_fork+0x1f/0x30

Fix it by calling kfree() accordingly.

Fixes: 38e44da5 ("thermal: int3400_thermal: process "thermal table changed" event")
Signed-off-by: Chuansheng Liu <chuansheng.liu@intel.com>
Cc: 4.14+ <stable@vger.kernel.org> # 4.14+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>