framework: consistent usage of PIGLIT_CONFIG.read_file param
Since, 1fc96325357b225f517cc35d874bbb9b2697281b, read_file is called
with both a pathname and an open file handle. It is clear that it is
meant to be called with a pathname.
Fixes: ef87faef0 ("Make it work with the latest pytest version")
Closes: https://gitlab.freedesktop.org/mesa/piglit/-/issues/70
Edited by Mark Janes