arm64: zynqmp: Fix open drain warning on ZynqMP

Mark both GPIO lines as GPIO_OPEN_DRAIN which is required by i2c-gpio DT
binding. Similar change was done by commit 8df80c18 ("ARM: dts: exynos:
Convert to new i2c-gpio bindings").

Signed-off-by: Manikanta Guntupalli <manikanta.guntupalli@amd.com>
Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/a0faf488dde310e1c1c1a676c371e223db6bdca6.1686227712.git.michal.simek@amd.com