Revert "iio: bmg160: IIO_BUFFER and IIO_TRIGGERED_BUFFER are required"

This reverts commit 35c45e8bce3c92fb1ff94d376f1d4bfaae079d66 which was
commit 06d2f6ca5a38abe92f1f3a132b331eee773868c3 upstream as it should
not have been applied.


Reported-by: Luis Henriques <luis.henriques@canonical.com>
Cc: Markus Pargmann <mpa@pengutronix.de>
Cc: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Cc: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>