libsensors: Allow IIO max sample rate to be configured via properties

libsensors: Allow IIO max sample rate to be configured via properties

Different hubs have different behavior.  Really we want to probe this
out of the hardware, but for HID sensors on I2C (as opposed to USB)
userspace doesn't get access to the descriptor right now.

Change-Id: I8bcd077509b43bba6025ca5f55ba9373db89cd8b
For: AXIA-3287
Signed-off-by: Andy Ross <andy.ross@windriver.com>
Reviewed-on: https://otc-android.intel.com/gerrit/22151
Tested-by: jenkins autobuilder
Reviewed-by: Russell Webb <russell.webb@intel.com>