ARC: boot: Support Halt-on-reset and Run-on-reset SMP booting modes

For Run-on-reset, non masters need to spin wait. For Halt-on-reset they
can jump to entry point directly.

Also while at it, made reset vector handler as "the" entry point for
kernel including host debugger based boot (which uses the ELF header
entry point)

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
index f50ff98..cc93896 100644
--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -194,6 +194,16 @@
 	range 2 4096
 	default "4"
 
+config ARC_SMP_HALT_ON_RESET
+	bool "Enable Halt-on-reset boot mode"
+	default y if ARC_UBOOT_SUPPORT
+	help
+	  In SMP configuration cores can be configured as Halt-on-reset
+	  or they could all start at same time. For Halt-on-reset, non
+	  masters are parked until Master kicks them so they can start of
+	  at designated entry point. For other case, all jump to common
+	  entry point and spin wait for Master's signal.
+
 endif	#SMP
 
 menuconfig ARC_CACHE