mm, printk: introduce new format %pGt for page_type

%pGp format is used to display 'flags' field of a struct page.  However,
some page flags (i.e.  PG_buddy, see page-flags.h for more details) are
stored in page_type field.  To display human-readable output of page_type,
introduce %pGt format.

It is important to note the meaning of bits are different in page_type. 
if page_type is 0xffffffff, no flags are set.  Setting PG_buddy
(0x00000080) flag results in a page_type of 0xffffff7f.  Clearing a bit
actually means setting a flag.  Bits in page_type are inverted when
displaying type names.

Only values for which page_type_has_type() returns true are considered as
page_type, to avoid confusion with mapcount values.  if it returns false,
only raw values are displayed and not page type names.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Hyeonggon Yoo <[email protected]>
Reviewed-by: Petr Mladek <[email protected]>	[vsprintf part]
Cc: Andy Shevchenko <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Joe Perches <[email protected]>
Cc: John Ogness <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Cc: Steven Rostedt (Google) <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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