dt-bindings: HID: i2c-hid: elan: add Elan eKTH5015M

dt-bindings: HID: i2c-hid: elan: add Elan eKTH5015M

Add a compatible string for the Elan eKTH5015M touch controller.

Judging from the current binding and commit bd3cba00dcc6 ("HID: i2c-hid:
elan: Add support for Elan eKTH6915 i2c-hid touchscreens"), eKTH5015M
appears to be compatible with eKTH6915. Notably the power-on sequence is
the same.

While at it, drop a redundant label from the example.

Reviewed-by: Krzysztof Kozlowski <[email protected]>
Signed-off-by: Johan Hovold <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Benjamin Tissoires <[email protected]>