arm64: dts: phycore-imx8mm: Label typo-fix of VPU

arm64: dts: phycore-imx8mm: Label typo-fix of VPU

BugLink: https://bugs.launchpad.net/bugs/2038236
[ Upstream commit cddeefc1663294fb74b31ff5029a83c0e819ff3a ]

Corrected the label of the VPU regulator node (buck 3)
from reg_vdd_gpu to reg_vdd_vpu.

Fixes: ae6847f26ac9 ("arm64: dts: freescale: Add phyBOARD-Polis-i.MX8MM support")
Signed-off-by: Yashwanth Varakala <y.varakala@phytec.de>
Signed-off-by: Cem Tenruh <c.tenruh@phytec.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>