soc: samsung: chipid: Convert exynos-chipid driver to use the regmap API

Convert the driver to use regmap API in order to allow other
drivers, like ASV, to access the CHIPID registers.

Add definition of selected CHIPID register offsets and register bit
fields for Exynos5422 SoC.

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>