ANDROID: fs: Refactor FS readpage/write tracepoints.

Refactor the fs readpage/write tracepoints to move the
inode->path lookup outside the tracepoint code, and pass a pointer
to the path into the tracepoint code instead. This is necessary
because the tracepoint code runs non-preemptible. Thanks to
Trilok Soni for catching this in 4.4.

Signed-off-by: Mohan Srinivasan <srmohan@google.com>

[AmitP: Folded following android-4.9 commit changes into this patch
        a5c4dbb05ab7 ("ANDROID: Replace spaces by '_' for some android filesystem tracepoints.")]
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>