Staging: fix more iio builds when IIO_RING_BUFFER is not enabled

Fix lots more build errors in staging/iio when CONFIG_IIO_RING_BUFFER
is not enabled by moving enums and defines outside of the
CONFIG_IIO_RING_BUFFER ifdef block.

Examples (one from each driver; there were 116 total errors):

drivers/staging/iio/accel/adis16204_core.c:437: error: 'ADIS16204_SCAN_SUPPLY' undeclared here (not in a function)
drivers/staging/iio/accel/adis16209_core.c:410: error: 'ADIS16209_SCAN_SUPPLY' undeclared here (not in a function)
drivers/staging/iio/gyro/adis16260_core.c:420: error: 'ADIS16260_SCAN_GYRO' undeclared here (not in a function)
drivers/staging/iio/imu/adis16400_core.c:565: error: 'ADIS16400_SCAN_SUPPLY' undeclared here (not in a function)

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Acked-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>