ti: keystone: Migrate CONFIG_SOC_K2* to Kconfig

Move the individual keystone 2 SoC symbols to the mach Kconfig file,
select them as needed.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/arm/mach-keystone/Kconfig b/arch/arm/mach-keystone/Kconfig
index e06eba5..94e6fe1 100644
--- a/arch/arm/mach-keystone/Kconfig
+++ b/arch/arm/mach-keystone/Kconfig
@@ -6,6 +6,7 @@
 
 config TARGET_K2HK_EVM
 	bool "TI Keystone 2 Kepler/Hawking EVM"
+	select SOC_K2HK
 	select SPL_BOARD_INIT if SPL
 	select CMD_DDR3
 	imply DM_I2C
@@ -14,6 +15,7 @@
 
 config TARGET_K2E_EVM
 	bool "TI Keystone 2 Edison EVM"
+	select SOC_K2E
 	select SPL_BOARD_INIT if SPL
 	select CMD_DDR3
 	imply DM_I2C
@@ -22,6 +24,7 @@
 
 config TARGET_K2L_EVM
 	bool "TI Keystone 2 Lamar EVM"
+	select SOC_K2L
 	select SPL_BOARD_INIT if SPL
 	select CMD_DDR3
 	imply DM_I2C
@@ -31,6 +34,7 @@
 config TARGET_K2G_EVM
 	bool "TI Keystone 2 Galileo EVM"
         select BOARD_LATE_INIT
+	select SOC_K2G
 	select SPL_BOARD_INIT if SPL
         select TI_I2C_BOARD_DETECT
 	select CMD_DDR3
@@ -40,6 +44,18 @@
 
 endchoice
 
+config SOC_K2E
+	bool
+
+config SOC_K2G
+	bool
+
+config SOC_K2HK
+	bool
+
+config SOC_K2L
+	bool
+
 config SYS_SOC
 	default "keystone"