scripts/gdb: fix lx-timerlist for Python3

Below incompatibilities between Python2 and Python3 made lx-timerlist fail
to run under Python3.

o xrange() is replaced by range() in Python3
o bytes and str are different types in Python3
o the return value of Inferior.read_memory() is memoryview object in
  Python3

akpm: cc stable so that older kernels are properly debuggable under newer
Python.

Link: https://lkml.kernel.org/r/TYCP286MB2146EE1180A4D5176CBA8AB2C6819@TYCP286MB2146.JPNP286.PROD.OUTLOOK.COMSigned-off-by: Peng Liu <liupeng17@lenovo.com>
Reviewed-by: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Kieran Bingham <kbingham@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

scripts/gdb/linux/timerlist.py

@@ -72,7 +72,7 @@ def print_cpu(hrtimer_bases, cpu, max_clock_bases):
     ts = cpus.per_cpu(tick_sched_ptr, cpu)
 
     text = "cpu: {}\n".format(cpu)
-    for i in xrange(max_clock_bases):
+    for i in range(max_clock_bases):
         text += " clock {}:\n".format(i)
         text += print_base(cpu_base['clock_base'][i])
 
@@ -157,6 +157,8 @@ def pr_cpumask(mask):
     num_bytes = (nr_cpu_ids + 7) / 8
     buf = utils.read_memoryview(inf, bits, num_bytes).tobytes()
     buf = binascii.b2a_hex(buf)
+    if type(buf) is not str:
+        buf=buf.decode()
 
     chunks = []
     i = num_bytes

scripts/gdb/linux/utils.py

@@ -88,7 +88,10 @@ def get_target_endianness():
 
 
 def read_memoryview(inf, start, length):
-    return memoryview(inf.read_memory(start, length))
+    m = inf.read_memory(start, length)
+    if type(m) is memoryview:
+        return m
+    return memoryview(m)
 
 
 def read_u16(buffer, offset):