mm: remove duplicate asm/mman.h files

A number of architectures have identical asm/mman.h files so they can all
be merged by using the new generic file.

The remaining asm/mman.h files are substantially different from each
other.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>