linux-gumstix 3.5: backport patch for mt9v032 module problem 

The standard kernel build has support for the mt9v032 "Caspa" camera, but if
one is not installed the hardware probe fails.  In this situation a driver
bug caused the module reference count to be decremented too many times,
making it impossible to unload the module, for example to allow the module
supporting a different camera to be loaded instead.

NB: This upstream patch first appeared in Linux 3.9 and was modified to
reflect the location of the sources in the 3.5 kernel.

**Note** I've updated the [kernel collected patch branch](https://github.com/pabigot/linux/tree/gumstix/dylan/linux-gumstix-3.5) to include this one.  The linux-gumstix-3.5.7.bb recipe documents that the omap-3.5 branch of the gumstix linux repo contains these patches, but it does not.  This discrepancy should be reconciled by either updating the branch or changing the recipe documentation.  (Note that the recipe and the branch are intentionally based on v3.5 not on whatever update version is actively used; this simplifies generating the patches for meta-gumstix by using "git format-patch v3.5" and adding the new ones in the correct, linearly increasing, order.)