arm64: dts: imx8mp-phyboard-pollux-rdk: correct uart pad settings

arm64: dts: imx8mp-phyboard-pollux-rdk: correct uart pad settings

BugLink: https://bugs.launchpad.net/bugs/1987451
[ Upstream commit e266c155bd88e95f9b86379d6b0add6ac6e5452e ]

BIT3 and BIT0 are reserved bits, should not touch.

Fixes: 846f752866bd ("arm64: dts: imx8mp-phyboard-pollux-rdk: Change debug UART")
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
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>