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

This file is created in 2a0d45ae6c 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.

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

src/freedreno/Makefile.sources

@@ -39,6 +39,7 @@ ir3_SOURCES := \
 	ir3/ir3_nir_lower_load_barycentric_at_offset.c \
 	ir3/ir3_nir_lower_io_offsets.c \
 	ir3/ir3_nir_lower_tess.c \
+	ir3/ir3_nir_lower_tex_prefetch.c \
 	ir3/ir3_nir_lower_tg4_to_tex.c \
 	ir3/ir3_nir_move_varying_inputs.c \
 	ir3/ir3_print.c \