tools: kvm_stat: Powerpc related fixes

kvm_stat script is failing to execute on powerpc :
 # ./kvm_stat
Traceback (most recent call last):
  File "./kvm_stat", line 825, in <module>
    main()
  File "./kvm_stat", line 813, in main
    providers = get_providers(options)
  File "./kvm_stat", line 778, in get_providers
    providers.append(TracepointProvider())
  File "./kvm_stat", line 416, in __init__
    self.filters = get_filters()
  File "./kvm_stat", line 315, in get_filters
    if ARCH.exit_reasons:
AttributeError: 'ArchPPC' object has no attribute 'exit_reasons'

This is because, its trying to access a non-defined attribute.

Also, the IOCTL number of RESET is incorrect for powerpc. The correct
number has been added.
Signed-off-by: Hemant Kumar <hemant@linux.vnet.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

tools/kvm/kvm_stat/kvm_stat

@@ -256,11 +256,13 @@ class ArchPPC(Arch):
         self.ioctl_numbers = IOCTL_NUMBERS
         self.ioctl_numbers['ENABLE'] = 0x20002400
         self.ioctl_numbers['DISABLE'] = 0x20002401
+        self.ioctl_numbers['RESET'] = 0x20002403
 
         # PPC comes in 32 and 64 bit and some generated ioctl
         # numbers depend on the wordsize.
         char_ptr_size = ctypes.sizeof(ctypes.c_char_p)
         self.ioctl_numbers['SET_FILTER'] = 0x80002406 | char_ptr_size << 16
+        self.exit_reasons = {}
 
 class ArchA64(Arch):
     def __init__(self):