freedreno/ir3: Add missing ir3_nir_lower_tex_prefetch.c to Android.mk

This file is created in 2a0d45ae but addition to android makefiles was omitted. It breaks the build with missing references which are defined in this file. List the file in ir3_SOURCES to make the build succeed.

@robclark Another small fixup, as outsider (not a listed contributor) I am unable to assign the proper tag so I'll ping you directly, if that's okay.

EDIT: Looks like I accidentally pushed some debug commits to the wrong remote. Sorry for the noise, they are removed from the branch now.

Signed-off-by: Marijn Suijten marijns95@gmail.com