xtensa: dispatch medium-priority interrupts

Add support for dispatching medium-priority interrupts, that is,
interrupts of priority levels 2 to EXCM_LEVEL. IRQ handling may be
preempted by higher priority IRQ.

Signed-off-by: Marc Gauthier <marc@tensilica.com>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
diff --git a/arch/xtensa/include/asm/regs.h b/arch/xtensa/include/asm/regs.h
index 76096a4..b24de67 100644
--- a/arch/xtensa/include/asm/regs.h
+++ b/arch/xtensa/include/asm/regs.h
@@ -88,6 +88,7 @@
 #define PS_UM_BIT		5
 #define PS_EXCM_BIT		4
 #define PS_INTLEVEL_SHIFT	0
+#define PS_INTLEVEL_WIDTH	4
 #define PS_INTLEVEL_MASK	0x0000000F
 
 /*  DBREAKCn register fields.  */