iio: Documentation change for inkern interface.

This commit- 314be14bb renamed the _st_ functions to loose the bit
that was meant for staging version but forgot to change
the documentation which still have _st_ sprinkled in some of the
places.

Signed-off-by: anish kumar <[e-mail]>
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/staging/iio/Documentation/inkernel.txt

···
 about this channel such as it's current reading.
 
 e.g.
-iio_st_read_channel_raw() - get a reading
-iio_st_read_channel_type() - get the type of channel
+iio_read_channel_raw() - get a reading
+iio_get_channel_type() - get the type of channel
 
 There is also provision for retrieving all of the channels associated
 with a given consumer.  This is useful for generic drivers such as
 iio_hwmon where the number and naming of channels is not known by the
-consumer driver.  To do this, use iio_st_channel_get_all.
+consumer driver.  To do this, use iio_channel_get_all.