arm64: dts: exynos: Use macros for pinctrl configuration on Exynos7

Usage of DTS macros instead of hard-coded numbers makes code easier to
read.  One does not have to remember which value means pull-up/down or
specific driver strength.

Signed-off-by: Pankaj Dubey <pankaj.dubey@samsung.com>
Reviewed-by: Alim Akhtar <alim.akhtar@samsung.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>