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

[ Upstream commit HEAD ]

This reverts commit 279c039ca63acbd69e69d6d7ddfed50346fb2185 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>

(cherry picked from commit 934d9b907aeec5f344ca801ed7361551199dfc69)
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>