staging/android: Initial partial kernel-doc for ashmem.c

I am beginning to understand the core concepts at play here.

I am nowhere near finished with this class - However, it is better if
I commit what I have documented so far tonight - That way, if I mess
up tomorrow morning, I can just roll back to here.

Sorry if this clutters things up. In the end, once *everything* is
documented, it will make understanding the Android staging driver
easier to understand as a programmer - Hopefully for both new developers
and current ones.

Signed-off-by: Cruz Julian Bishop <cruzjbishop@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>