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>

arch/arc/kernel/entry-arcv2.S

@@ -24,7 +24,7 @@
 	.align 4
 
 # Initial 16 slots are Exception Vectors
-VECTOR	stext			; Restart Vector (jump to entry point)
+VECTOR	res_service		; Reset Vector
 VECTOR	mem_service		; Mem exception
 VECTOR	instr_service		; Instrn Error
 VECTOR	EV_MachineCheck		; Fatal Machine check