i2c: S3C24X0: Finish Kconfig migration

Finish moving this driver to Kconfig.
- Update the dependency logic for Exynos5 too
- Remove the unused CONFIG_SYS_I2C_S3C24X0_SPEED variable
- Drop CONFIG_SYS_I2C_S3C24X0_SLAVE as it's always set to 0.
- Move the internal SYS_I2C_S3C24X0_SLAVE define closer to the only user.

Cc: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Minkyu Kang <mk7.kang@samsung.com>
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>
diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig
index 63d03a3..a50c1f3 100644
--- a/drivers/i2c/Kconfig
+++ b/drivers/i2c/Kconfig
@@ -449,7 +449,7 @@
 
 config SYS_I2C_S3C24X0
 	bool "Samsung I2C driver"
-	depends on ARCH_EXYNOS4 && DM_I2C
+	depends on (ARCH_EXYNOS4 || ARCH_EXYNOS5) && DM_I2C
 	help
 	  Support for Samsung I2C controller as Samsung SoCs.