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

RFC: 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.

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
        4bfd054ae11e ("fs: fold __inode_permission() into inode_permission()").

        Also introduce vfs_mkobj2(), because do_create()
        moved from using vfs_create() to vfs_mkobj()
        eecec19d9e70 ("mqueue: switch to vfs_mkobj(), quit abusing ->d_fsdata")

        do_create() is dropped/cleaned up upstream so a
        minor refactoring there as well.
        066cc813e94a ("do_mq_open(): move all work prior to dentry_open() into a helper")]
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>