xtensa: fix arch_irqs_disabled_flags implementation

IRQs are disabled when PS.EXCM is set or PS.INTLEVEL is equal to or
higher than LOCKLEVEL.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>

arch/xtensa/include/asm/irqflags.h

@@ -47,7 +47,10 @@ static inline void arch_local_irq_restore(unsigned long flags)
 
 static inline bool arch_irqs_disabled_flags(unsigned long flags)
 {
-	return (flags & 0xf) != 0;
+#if XCHAL_EXCM_LEVEL < LOCKLEVEL || (1 << PS_EXCM_BIT) < LOCKLEVEL
+#error "XCHAL_EXCM_LEVEL and 1<<PS_EXCM_BIT must be no less than LOCKLEVEL"
+#endif
+	return (flags & (PS_INTLEVEL_MASK | (1 << PS_EXCM_BIT))) >= LOCKLEVEL;
 }
 
 static inline bool arch_irqs_disabled(void)