device-lg-hammerhead: add GSK_RENDERER workaround

As mentioned in this MR: !4952 (closed) (thanks to @minlexx) Adding this script to the hammerhead; GTK4 apps launch with heavy visual artifacts unless this is set.

Example:

The msm8916 package has a gpu subpackage but I don't think that's quite necessary for this for just one script. If that's preferable I'll set it like that too.