ARM: dts: imx: make gpt node name generic

[ Upstream commit 7c48b086965873c0aa93d99773cf64c033b76b2f ]

Node name should be generic, use "timer" instead of "gpt" for gpt node.

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Stable-dep-of: 397caf68e2d3 ("ARM: dts: imx7: Declare timers compatible with fsl,imx6dl-gpt")
Signed-off-by: Sasha Levin <sashal@kernel.org>