ARM: dts: exynos: Correct Trats2 panel reset line

Trats2 uses gpf2-1 as the panel reset GPIO. gpy4-5 was only used
on early revisions of the board.

Fixes: 420ae845 ("ARM: dts: exynos4412-trats2: add panel node")
Signed-off-by: Simon Shields <simon@lineageos.org>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>