This reverts commit 9ce650a7.

This commit causes watchdog lockups on my machine, and while I have no
idea what the cause is, it bisected right to this commit, and reverting
the change promptly fixes it.

At least occasionally one of the watchdog call traces was

  Call Trace:
    _raw_spin_lock_irqsave+0x35/0x40
    snd_pcm_period_elapsed+0x1b/0xa0 [snd_pcm]
    snd_usb_endpoint_start+0x1a0/0x3c0 [snd_usb_audio]
    start_endpoints+0x23/0x90 [snd_usb_audio]
    snd_usb_substream_playback_trigger+0x7b/0x1a0 [snd_usb_audio]
    snd_pcm_common_ioctl+0x1c44/0x2360 [snd_pcm]
    snd_pcm_ioctl+0x2e/0x40 [snd_pcm]
    __se_sys_ioctl+0x72/0xc0
    do_syscall_64+0x4c/0xa0
    entry_SYSCALL_64_after_hwframe+0x44/0xae

so presumably it's a locking error on that substream spinlock that
snd_pcm_period_elapsed() takes.  But at this point I just want to have a
working system so that I can continue the merge window work tomorrow.

Cc: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>