ARC: Fix detection of dual-issue enabled

As per PRM bit #0 ("D") in EXEC_CTRL enables dual-issue if set to 0,
otherwise if set to 1 all instructions are executed one at a time,
i.e. dual-issue is disabled.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

arch/arc/kernel/setup.c

@@ -199,7 +199,7 @@ static void read_arc_build_cfg_regs(void)
 			unsigned int exec_ctrl;
 
 			READ_BCR(AUX_EXEC_CTRL, exec_ctrl);
-			cpu->extn.dual_enb = exec_ctrl & 1;
+			cpu->extn.dual_enb = !(exec_ctrl & 1);
 
 			/* dual issue always present for this core */
 			cpu->extn.dual = 1;