Move CONFIG_PANIC_HANG to Kconfig

Freescale (NXP) boards have lots of defconfig files per board.
I used "imply PANIC_HANG" for them.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: York Sun <york.sun@nxp.com>
diff --git a/arch/arm/cpu/armv8/fsl-layerscape/Kconfig b/arch/arm/cpu/armv8/fsl-layerscape/Kconfig
index 66bc32c..6c03dfb 100644
--- a/arch/arm/cpu/armv8/fsl-layerscape/Kconfig
+++ b/arch/arm/cpu/armv8/fsl-layerscape/Kconfig
@@ -11,6 +11,7 @@
 	select SYS_FSL_ERRATUM_A009008
 	select ARCH_EARLY_INIT_R
 	select BOARD_EARLY_INIT_F
+	imply PANIC_HANG
 
 config ARCH_LS1043A
 	bool
@@ -91,6 +92,7 @@
 	select ARCH_EARLY_INIT_R
 	select BOARD_EARLY_INIT_F
 	imply SCSI
+	imply PANIC_HANG
 
 config ARCH_LS2080A
 	bool
@@ -129,6 +131,7 @@
 	select SYS_FSL_ERRATUM_A009203
 	select ARCH_EARLY_INIT_R
 	select BOARD_EARLY_INIT_F
+	imply PANIC_HANG
 
 config FSL_LSCH2
 	bool