LOCAL_STORAGE.zw is workgroup local memory, whereas LOCAL_STORAGE.xy is
thread local memory. Likewise PC_SP.zw is the stack pointer, which is
initialized to (LOCAL_STORAGE.zw + offset) but is modifiable by the
shader. Panfrost doesn't modify the s tack pointer, and the register
allocation logic assumes a zero offset, so let's always spill to thread
local memory = LOCAL_STORAGE.xy, as was intended by Italo's cleanup.

This is visible on any shader that spills. Compute shaders aren't
advertised yet, so WLS will be null, causing a fault like the following
(reproduced on Mali T860 with the glyphy trace):

[15634.148873] panfrost ff9a0000.gpu: Unhandled Page fault in AS0 at VA 0x0000000000000000
          Reason: TODO
          raw fault status: 0x70003C2
          decoded fault status: SLAVE FAULT
          exception type 0xC2: TRANSLATION_FAULT_LEVEL2
          access type 0x3: WRITE
          source id 0x700
[15634.658170] panfrost ff9a0000.gpu: gpu sched timeout, js=0, config=0x3300, status=0x8, head=0x31d4540,
tail=0x31d4540, sched_job=00000000e8101b2e

Fixes: 6a12ea02

 ("pan/mdg: properly encode/decode ldst instructions")
Signed-off-by: Alyssa Rosenzweig <alyssa@collabora.com>
Part-of: <!10866>