Add TM4C123 to the configuration system

arch/arm/src/tiva/Kconfig

@@ -48,6 +48,13 @@ config ARCH_CHIP_LM4F120
 	select ARCH_CHIP_LM4F
 	select ARCH_HAVE_FPU
 
+config CONFIG_ARCH_CHIP_TM4C123GH6ZRB
+	bool "TM4C123GH6ZRB"
+	depends on ARCH_CHIP_TIVA
+	select ARCH_CORTEXM4
+	select ARCH_CHIP_TM4C
+	select ARCH_HAVE_FPU
+
 endchoice
 
 # Chip families