arm: samsung: Migrate a number of symbols to Kconfig

- In a number of cases, use CONFIG_ARCH_EXYNOS[45] rather than
  CONFIG_EXYNOS[45]
- In other cases, test for CONFIG_ARCH_EXYNOS or CONFIG_ARCH_S5PC1XX
- Migrate specific SoC CONFIG values to Kconfig
- Use CONFIG_TARGET_x rather than CONFIG_x
- Migrate other CONFIG_EXYNOS_x symbols to Kconfig
- Reference CONFIG_EXYNOS_RELOCATE_CODE_BASE directly as EXYNOS_RELOCATE_CODE_BASE
- Rename CONFIG_S5P_PA_SYSRAM to CONFIG_SMP_PEN_ADDR to match the rest
  of U-Boot usage.

Cc: Minkyu Kang <mk7.kang@samsung.com>
Signed-off-by: Tom Rini <trini@konsulko.com>