panfrost: Fix texture field size

I have to imagine this was UB.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4844>
diff --git a/src/panfrost/include/panfrost-job.h b/src/panfrost/include/panfrost-job.h
index 924c4e4..051fe27 100644
--- a/src/panfrost/include/panfrost-job.h
+++ b/src/panfrost/include/panfrost-job.h
@@ -1264,7 +1264,7 @@
         unsigned swizzle : 12;
         enum mali_texture_layout layout : 4;
         uint8_t levels : 8; /* Number of levels-1 if mipmapped, 0 if not */
-        unsigned unk1 : 4;
+        unsigned unk1 : 8;
 
         unsigned levels_unk : 24; /* 0 */
         unsigned level_2 : 8; /* Number of levels, again? */