vfs: renumber FMODE_NONOTIFY and add to uniqueness check

Fix clashing values for O_PATH and FMODE_NONOTIFY on sparc.
The clashing O_PATH value was added in 5229645bdc35f1cc43eb ("vfs: add
nonconflicting values for O_PATH") but this can't be changed as it
is user-visible.

FMODE_NONOTIFY is only used internally in the kernel, but it is in
the same numbering space as the other O_* flags, as indicated by the
comment at the top of include/uapi/asm-generic/fcntl.h (and its use
in fs/notify/fanotify/fanotify_user.c).  So renumber it to avoid
the clash.

All of this has happened before (12ed2e36c98aec6c4155, "fanotify:
FMODE_NONOTIFY and __O_SYNC in sparc conflict"), and all of this
will happen again -- so update the uniqueness check in fcntl_init()
to include __FMODE_NONOTIFY.

Signed-off-by: David Drysdale <drysdale@google.com>
Acked-by: David S. Miller <davem@davemloft.net>