arm64: dts: freescale: imx8mm-verdin: Fix GPU speed

arm64: dts: freescale: imx8mm-verdin: Fix GPU speed

BugLink: https://bugs.launchpad.net/bugs/2075154
[ Upstream commit 08f0fa5d6aa9488f752eb5410e32636f143b3d8e ]

The GPU clock was reduced on iMX8MM SOC device tree to prevent boards
that don't support GPU overdrive from being out of specification. However,
this caused a regression in GPU speed for the Verdin iMX8MM, which does
support GPU overdrive. This patch fixes this by enabling overdrive mode
in the SOM dtsi.

Fixes: 1f794d3eed53 ("arm64: dts: imx8mm: Reduce GPU to nominal speed")
Signed-off-by: Joao Paulo Goncalves <joao.goncalves@toradex.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>