mei: don't unset read cb ptr on reset

mei: don't unset read cb ptr on reset

commit 5cb906c7035f03a3a44fecece9d3ff8fcc75d6e0 upstream.

Don't set read callback to NULL during reset as
this leads to memory leak of both cb and its buffer.
The memory is correctly freed during mei_release.

The memory leak is detectable by kmemleak if
application has open read call while system is going through
suspend/resume.

unreferenced object 0xecead780 (size 64):
  comm "AsyncTask #1", pid 1018, jiffies 4294949621 (age 152.440s)
  hex dump (first 32 bytes):
    00 01 10 00 00 02 20 00 00 bf 30 f1 00 00 00 00  ...... ...0.....
    00 00 00 00 00 00 00 00 36 01 00 00 00 70 da e2  ........6....p..
  backtrace:
    [<c1a60aec>] kmemleak_alloc+0x3c/0xa0
    [<c131ed56>] kmem_cache_alloc_trace+0xc6/0x190
    [<c16243c9>] mei_io_cb_init+0x29/0x50
    [<c1625722>] mei_cl_read_start+0x102/0x360
    [<c16268f3>] mei_read+0x103/0x4e0
    [<c1324b09>] vfs_read+0x89/0x160
    [<c1324d5f>] SyS_read+0x4f/0x80
    [<c1a7b318>] syscall_call+0x7/0xb
    [<ffffffff>] 0xffffffff
unreferenced object 0xe2da7000 (size 512):
  comm "AsyncTask #1", pid 1018, jiffies 4294949621 (age 152.440s)
  hex dump (first 32 bytes):
    00 6c da e2 7c 00 00 00 00 00 00 00 c0 eb 0c 59  .l..|..........Y
    1b 00 00 00 01 00 00 00 02 10 00 00 01 00 00 00  ................
  backtrace:
    [<c1a60aec>] kmemleak_alloc+0x3c/0xa0
    [<c131f127>] __kmalloc+0xe7/0x1d0
    [<c162447e>] mei_io_cb_alloc_resp_buf+0x2e/0x60
    [<c162574c>] mei_cl_read_start+0x12c/0x360
    [<c16268f3>] mei_read+0x103/0x4e0
    [<c1324b09>] vfs_read+0x89/0x160
    [<c1324d5f>] SyS_read+0x4f/0x80
    [<c1a7b318>] syscall_call+0x7/0xb
    [<ffffffff>] 0xffffffff

Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>