ARM: dts: samsung: exynos5250: describe sromc bank memory map

ARM: dts: samsung: exynos5250: describe sromc bank memory map

According to public user manual for Exynos 5250 [1], the SROM
controller has 4 banks, at same addresses as for example Exynos
5410. Describe the bank memory map of the SoC.

[1] https://web.archive.org/web/20130921194458/http://www.samsung.com/global/business/semiconductor/file/product/Exynos_5_Dual_User_Manaul_Public_REV100-0.pdf

Signed-off-by: Henrik Grimler <henrik@grimler.se>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>