ARM: dts: exynos: fix UART3 pins configuration in Exynos5250

The gpa1-4 pin was put twice in UART3 pin configuration of Exynos5250,
instead of proper pin gpa1-5.

Fixes: f8bfe2b0 ("ARM: dts: add pin state information in client nodes for Exynos5 platforms")
Cc: <stable@vger.kernel.org>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Alim Akhtar <alim.akhtar@samsung.com>
Link: https://lore.kernel.org/r/20211230195325.328220-1-krzysztof.kozlowski@canonical.com