iio:light:tsl2563 move out of staging

This driver is simple, uses the latest interfaces and contains few if
any controversial elements.  All of its interfaces have been in place
for a long time now.  Hence let's move it out of staging.

Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Acked-by: Peter Meerwald <pmeerw@pmeerw.net>

include/linux/platform_data/tsl2563.h

@@ -0,0 +1,8 @@
+#ifndef __LINUX_TSL2563_H
+#define __LINUX_TSL2563_H
+
+struct tsl2563_platform_data {
+	int cover_comp_gain;
+};
+
+#endif /* __LINUX_TSL2563_H */