compat: backport simple_open()

compat: backport simple_open()

This is not yet upstream on Linus' tree so my best guess is
it will make it on the 3.5 release.

commit 90c936d19fb5cb3fb6b74dc18bf4bb3314a6a599
Author: Stephen Boyd <sboyd@codeaurora.org>
Date:   Wed Mar 21 10:48:20 2012 +1100

    libfs: add simple_open()

    debugfs and a few other drivers use an open-coded version of simple_open()
    to pass a pointer from the file to the read/write file ops.  Add support
    for this simple case to libfs so that we can remove the many duplicate
    copies of this simple function.

    Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
    Cc: Al Viro <viro@zeniv.linux.org.uk>
    Cc: Julia Lawall <Julia.Lawall@lip6.fr>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mcgrof@tux ~/compat (git::master)$ ckmake
Trying kernel                  3.3.0-030300rc2-generic	[OK]
Trying kernel                     3.2.2-030202-generic	[OK]
Trying kernel                    3.1.10-030110-generic	[OK]
Trying kernel                    3.0.18-030018-generic	[OK]
Trying kernel                  2.6.39-02063904-generic	[OK]
Trying kernel                  2.6.38-02063808-generic	[OK]
Trying kernel                  2.6.37-02063706-generic	[OK]
Trying kernel                  2.6.36-02063604-generic	[OK]
Trying kernel                  2.6.35-02063512-generic	[OK]
Trying kernel                  2.6.34-02063410-generic	[OK]
Trying kernel                  2.6.33-02063305-generic	[OK]
Trying kernel                  2.6.32-02063255-generic	[OK]
Trying kernel                  2.6.31-02063113-generic	[OK]
Trying kernel                  2.6.30-02063010-generic	[OK]
Trying kernel                  2.6.29-02062906-generic	[OK]
Trying kernel                  2.6.28-02062810-generic	[OK]
Trying kernel                    2.6.27-020627-generic	[OK]
Trying kernel                    2.6.26-020626-generic	[OK]
Trying kernel                    2.6.25-020625-generic	[OK]
Trying kernel                    2.6.24-020624-generic	[OK]

Signed-off-by: Luis R. Rodriguez <mcgrof@frijolero.org>