arm64: dts: imx8mm-kontron: Disable pullups for I2C signals on SL/BL i.MX8MM

There are external pullup resistors on the board and due to silicon
errata ERR050080 let's disable the internal ones to prevent any
unwanted behavior in case they wear out.

Fixes: 8668d8b2 ("arm64: dts: Add the Kontron i.MX8M Mini SoMs and baseboards")
Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>