media: saa7164: fix remove_proc_entry warning

media: saa7164: fix remove_proc_entry warning

if saa7164_proc_create() fails, saa7164_fini() will trigger a warning,

name 'saa7164'
WARNING: CPU: 1 PID: 6311 at fs/proc/generic.c:672 remove_proc_entry+0x1e8/0x3a0
  ? remove_proc_entry+0x1e8/0x3a0
  ? try_stop_module+0x7b/0x240
  ? proc_readdir+0x70/0x70
  ? rcu_read_lock_sched_held+0xd7/0x100
  saa7164_fini+0x13/0x1f [saa7164]
  __x64_sys_delete_module+0x30c/0x480
  ? __ia32_sys_delete_module+0x480/0x480
  ? __x64_sys_clock_gettime+0x11e/0x1c0
  ? __x64_sys_timer_create+0x1a0/0x1a0
  ? trace_hardirqs_off_caller+0x40/0x180
  ? do_syscall_64+0x18/0x450
  do_syscall_64+0x9f/0x450
  entry_SYSCALL_64_after_hwframe+0x49/0xbe

Fix it by checking the return of proc_create_single() before
calling remove_proc_entry().

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
[hverkuil-cisco@xs4all.nl: use 0444 instead of S_IRUGO]
[hverkuil-cisco@xs4all.nl: use pr_info instead of KERN_INFO]
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>