channel_get_pure_name needs to remove _blue/_green/_red prefix

[yongli3]

root@intel-corei7-64:/sys/bus/iio/devices/iio:device0# ls -l
drwxr-xr-x 2 root root 0 Oct 28 00:47 buffer
-r--r--r-- 1 root root 4096 Oct 28 00:47 dev
drwxr-xr-x 2 root root 0 Oct 28 00:47 events
-rw-r--r-- 1 root root 4096 Oct 28 00:47 in_intensity_blue_raw
-rw-r--r-- 1 root root 4096 Oct 28 00:47 in_intensity_clear_raw
-rw-r--r-- 1 root root 4096 Oct 28 00:47 in_intensity_green_raw
-rw-r--r-- 1 root root 4096 Oct 28 00:47 in_intensity_integration_time
-rw-r--r-- 1 root root 4096 Oct 28 00:47 in_intensity_red_raw
-rw-r--r-- 1 root root 4096 Oct 28 00:47 in_intensity_scale
-rw-r--r-- 1 root root 4096 Oct 28 00:47 in_proximity_raw
-rw-r--r-- 1 root root 4096 Oct 28 00:47 in_proximity_scale
-r--r--r-- 1 root root 4096 Oct 28 00:47 integration_time_available
-r--r--r-- 1 root root 4096 Oct 28 00:47 intensity_scale_available
-r--r--r-- 1 root root 4096 Oct 27 06:50 name
drwxr-xr-x 2 root root 0 Oct 28 00:47 power
-r--r--r-- 1 root root 4096 Oct 28 00:47 proximity_scale_available
drwxr-xr-x 2 root root 0 Oct 28 00:47 scan_elements
lrwxrwxrwx 1 root root 0 Oct 28 00:47 subsystem -> ../../../../../../bus/iio
-rw-r--r-- 1 root root 4096 Oct 27 06:49 uevent
root@intel-corei7-64:/sys/bus/iio/devices/iio:device0# cat name
apds9960

DBG: ./src/lib/io/sol-iio.c:165 craft_filename_path() available=4096, used=55, path='/sys/bus/iio/devices/iio:device0/in_intensity_red_scale'
DBG: ./src/lib/io/sol-iio.c:165 craft_filename_path() available=4096, used=45, path='/sys/bus/iio/devices/iio:device0/(null)_scale'
INF: ./src/lib/io/sol-iio.c:1091 channel_get_scale() Could not get scale for channel [in_intensity_red] in device0. Assuming 1.0