xtensa/mm: remove WANT_PAGE_VIRTUAL

This is not useful: it provides page->virtual and is used with highmem.
xtensa has no support for highmem and those HIGHMEM bits which are found
by grep are partly implemented.  The interesting functions like kmap() are
missing.  If someone actually implements the complete HIGHMEM support he
could use HASHED_PAGE_VIRTUAL like most others do.

Signed-off-by: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: Chris Zankel <chris@zankel.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>