There is a kmemleak when testing the media/i2c/ov2740.c with bpf mock
device:

unreferenced object 0xffff8881090e19e0 (size 16):
  comm "51-i2c-ov2740", pid 278, jiffies 4294781584 (age 23.613s)
  hex dump (first 16 bytes):
    00 f3 7c 0b 81 88 ff ff 80 75 6a 09 81 88 ff ff  ..|......uj.....
  backtrace:
    [<000000004e9fad8f>] __kmalloc_node+0x44/0x1b0
    [<0000000039c802f4>] kvmalloc_node+0x34/0x180
    [<000000009b8b5c63>] v4l2_ctrl_handler_init_class+0x11d/0x180
[videodev]
    [<0000000038644056>] ov2740_probe+0x37d/0x84f [ov2740]
    [<0000000092489f59>] i2c_device_probe+0x28d/0x680
    [<000000001038babe>] really_probe+0x17c/0x3f0
    [<0000000098c7af1c>] __driver_probe_device+0xe3/0x170
    [<00000000e1b3dc24>] device_driver_attach+0x34/0x80
    [<000000005a04a34d>] bind_store+0x10b/0x1a0
    [<00000000ce25d4f2>] drv_attr_store+0x49/0x70
    [<000000007d9f4e9a>] sysfs_kf_write+0x8c/0xb0
    [<00000000be6cff0f>] kernfs_fop_write_iter+0x216/0x2e0
    [<0000000031ddb40a>] vfs_write+0x658/0x810
    [<0000000041beecdd>] ksys_write+0xd6/0x1b0
    [<0000000023755840>] do_syscall_64+0x38/0x90
    [<00000000b2cc2da2>] entry_SYSCALL_64_after_hwframe+0x63/0xcd

ov2740_init_controls() won't clean all the allocated resources in fail
path, which may causes the memleaks. Add v4l2_ctrl_handler_free() to
prevent memleak.

Fixes: 866edc89 ("media: i2c: Add ov2740 image sensor driver")
Signed-off-by: Shang XiaoJing <shangxiaojing@huawei.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>