ARM: dts: imx53-tx53: use explicit pad_ctl settings for I2C pins

Don't rely on the padctl settings established by the boot loader, but
explicitly specify the padctl values in DTB. This is also necessary to
be able to use the DTB files from the Linux kernel for future U-Boot
versions that support HW configuration via DTB.

Signed-off-by: Lothar Waßmann <LW@KARO-electronics.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>