panfrost: Rename pan_instancing.c -> pan_attributes.c

Let's follow the naming convention that panfrost command stream code is
organized by command stream structure.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>

src/gallium/drivers/panfrost/Makefile.sources

@@ -22,7 +22,7 @@ C_SOURCES := \
 	pan_format.c \
 	pan_format.h \
 	pan_fragment.c \
-	pan_instancing.c \
+	pan_attributes.c \
 	pan_job.c \
 	pan_job.h \
 	pan_mfbd.c \

src/gallium/drivers/panfrost/meson.build

@@ -42,7 +42,7 @@ files_panfrost = files(
   'pan_blend_cso.c',
   'pan_compute.c',
   'pan_fragment.c',
-  'pan_instancing.c',
+  'pan_attributes.c',
   'pan_scoreboard.c',
   'pan_sfbd.c',
   'pan_mfbd.c',