[media] media: rc: nuvoton: switch attribute wakeup_data to text

Switch attribute wakeup_data from binary to a text attribute.
This makes it easier to handle in userspace and allows to
use the output of tools like mode2 almost as is to set a
wakeup sequence.
Changing to a text format and values in microseconds also
makes the userspace interface independent of the setting of
SAMPLE_PERIOD in the driver.

In addition document the new sysfs attribute in
Documentation/ABI/testing/sysfs-class-rc-nuvoton.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

Documentation/ABI/testing/sysfs-class-rc-nuvoton

@@ -0,0 +1,15 @@
+What:		/sys/class/rc/rcN/wakeup_data
+Date:		Mar 2016
+KernelVersion:	4.6
+Contact:	Mauro Carvalho Chehab <m.chehab@samsung.com>
+Description:
+		Reading this file returns the stored CIR wakeup sequence.
+		It starts with a pulse, followed by a space, pulse etc.
+		All values are in microseconds.
+		The same format can be used to store a wakeup sequence
+		in the Nuvoton chip by writing to this file.
+
+		Note: Some systems reset the stored wakeup sequence to a
+		factory default on each boot. On such systems store the
+		wakeup sequence in a file and set it on boot using e.g.
+		a udev rule.