When the CMI8738 FRAME2 register is read, the chip sometimes (probably
when wrapping around) returns an invalid value that would be outside the
programmed DMA buffer. This leads to an inconsistent PCM pointer that is
likely to result in an underrun.

To work around this, read the register multiple times until we get a
valid value; the error state seems to be very short-lived.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Reported-and-tested-by: Matija Nalis <mnalis-alsadev@voyager.hr>
Cc: <stable@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>