anv: fix a build race between generating a header and using it

anv_batch_chain.c includes genX_bits.h but doesn't ensure it gets generated first. This causes build failures, as observed here: https://autobuilder.yoctoproject.org/typhoon/#/builders/86/builds/1501/steps/8/logs/step2d

Signed-off-by: Alexander Kanavin alex.kanavin@gmail.com