ANDROID: vfs: Add permission2 for filesystems with per mount permissions

This allows filesystems to use their mount private data to
influence the permssions they return in permission2. It has
been separated into a new call to avoid disrupting current
permission users.

Bug: 35848445
Bug: 120446149
Change-Id: I9d416e3b8b6eca84ef3e336bd2af89ddd51df6ca
Signed-off-by: Daniel Rosenberg <drosen@google.com>
[AmitP: Minor refactoring of original patch to align with
        changes from the following upstream commit
        4bfd054a ("fs: fold __inode_permission() into inode_permission()").
        Also introduce vfs_mkobj2(), because do_create()
        moved from using vfs_create() to vfs_mkobj()
        eecec19d ("mqueue: switch to vfs_mkobj(), quit abusing ->d_fsdata")
        do_create() is dropped/cleaned-up upstream so a
        minor refactoring there as well.
        066cc813 ("do_mq_open(): move all work prior to dentry_open() into a helper")]
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
[astrachan: Folded the following changes into this patch:
            f46c9d62dd81 ("ANDROID: fs: Export vfs_rmdir2")
            9992eb8b9a1e ("ANDROID: xattr: Pass EOPNOTSUPP to permission2")]
Signed-off-by: Alistair Strachan <astrachan@google.com>