android: freedreno/ir3: simplify generated sources rules

android: freedreno/ir3: simplify generated sources rules

Simplification and alignment with meson's sources generation rules

Changelog:
- move rules from src/gallium/drivers/freedreno/Android.gen.mk to Android.ir3.mk
- simplify LOCAL_GENERATED_SOURCES based on $(ir3_GENERATED_FILES)
- remove includes of src/gallium/drivers/freedreno/Android.gen.mk
- remove src/gallium/drivers/freedreno/Android.gen.mk

Signed-off-by: Mauro Rossi <issor.oruam@gmail.com>
Acked-by: Rob Clark <robdclark@gmail.com>
Acked-by: Eric Engestrom <eric@engestrom.ch>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5580>