numa: Fix format string for "Invalid node" message

Some compilers complain about the PRIu16 format string with the
MAX(src, dst) and MAX_NODES arguments.  Example output from Apple LLVM
version 7.3.0 (clang-703.0.31):

  numa.c:236:20: warning: format specifies type 'unsigned short' but the argument has type 'int' [-Wformat]
                     MAX(src, dst), MAX_NODES);
  ~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
  include/qapi/error.h:163:35: note: expanded from macro 'error_setg'
                          (fmt), ## __VA_ARGS__)
                                    ^~~~~~~~~~~
  glib/2.52.2/include/glib-2.0/glib/gmacros.h:288:20: note: expanded from macro 'MAX'
  #define MAX(a, b)  (((a) > (b)) ? (a) : (b))
                     ^~~~~~~~~~~~~~~~~~~~~~~~~
  numa.c:236:35: warning: format specifies type 'unsigned short' but the argument has type 'int' [-Wformat]
                     MAX(src, dst), MAX_NODES);
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~
  include/qapi/error.h:163:35: note: expanded from macro 'error_setg'
                          (fmt), ## __VA_ARGS__)
                                    ^~~~~~~~~~~
  include/sysemu/sysemu.h:165:19: note: expanded from macro 'MAX_NODES'
  #define MAX_NODES 128
                    ^~~
MAX(src, dst) promotes the src and dst arguments to int, and MAX_NODES
is an int.  Use %d to silence those warnings.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Message-Id: <20170530184013.31044-1-ehabkost@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>