agx: Plumb in store instruction

This will be used for compute kernels (and transform feedback) in the (near)
future. For now, let's get the opcode plumbed in the backend to reduce some of
the rebase pain.

Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/20446>

src/asahi/compiler/agx_opcodes.py

@@ -239,6 +239,12 @@ op("device_load",
       encoding_32 = (0x05, 0x7F, 6, 8),
       srcs = 2, imms = [FORMAT, MASK, SHIFT, SCOREBOARD], can_reorder = False)
 
+# sources are value, base, index
+# TODO: Consider permitting the short form
+op("device_store",
+      encoding_32 = (0x45 | (1 << 47), 0, 8, _),
+      dests = 0, srcs = 3, imms = [FORMAT, MASK, SHIFT, SCOREBOARD], can_eliminate = False)
+
 # sources are value, index
 # TODO: Consider permitting the short form
 op("uniform_store",