ARM: dts: imx6sl-warp: correct vendor in compatible to Revotics

The WaRP board (Wearable Development Platform) was apparently made by
Revolution Robotics, Inc (brand: Revotics), not by "Warp".  Correct the
vendor in compatible to reflect this.  The compatibles were not
documented in the bindings before.

Link: https://revotics.com/warp


Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>