Revert "i965/tex_image: Reference the renderbuffer miptree in setTexBuffer2"

Revert "i965/tex_image: Reference the renderbuffer miptree in setTexBuffer2"

This reverts commit d80cbbeaff9329fdc78ae3d97097c1e65dfcdd61.

It turns out that formats do matter - the framebuffer's miptree has an
sRGB format, and the one we created did not.  This broke rendering when
using KWin compositing, GNOME Terminal Fedora (with a transparent
background), and Qt menu rendering in general, to name a few.

It's been a month and this hasn't been fixed, and I'm sick of reverting
this patch or applying NAK'd hacks and restarting various programs at
random times every day, multiple times a day, to keep my desktop
environment functional.

The only benefit of this patch was to prepare the way for modifiers,
which AFAIK aren't finished yet anyway, so there's really no downside
to reverting it.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=102924