intel_idle: correct BXT support

Commit 5dcef69486 ("intel_idle: add BXT support") added an 8-element
lookup array with just a 2-bit value used for lookups. As per the SDM
that bit field is really 3 bits wide. While this is supposedly benign
here, future re-use of the code for other CPUs might expose the issue.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/idle/intel_idle.c

@@ -1190,7 +1190,7 @@ static unsigned long long irtl_2_usec(unsigned long long irtl)
 	if (!irtl)
 		return 0;
 
-	ns = irtl_ns_units[(irtl >> 10) & 0x3];
+	ns = irtl_ns_units[(irtl >> 10) & 0x7];
 
 	return div64_u64((irtl & 0x3FF) * ns, 1000);
 }