Fix NameError in _BlockSizes caused by removed constant

Author: Perseus14

src/maxdiffusion/kernels/custom_splash_attention.py

@@ -30,14 +30,11 @@
 NUM_SUBLANES = 8
 NT_DIM_NUMBERS = (((1,), (1,)), ((), ()))
 
-# Kept at 256 to protect VPU registers (V1 Optimization)
-DEFAULT_BKVCOMPUTEINSIZE = 256
-
 
 class _BlockSizes:
   __slots__ = ("block_q", "block_kv", "block_kv_compute", "block_kv_compute_in")
 
-  def __init__(self, block_q: int, block_kv: int, block_kv_compute: int | None = None, block_kv_compute_in: int = DEFAULT_BKVCOMPUTEINSIZE):
+  def __init__(self, block_q: int, block_kv: int, block_kv_compute: int | None = None, block_kv_compute_in: int = 256):
     self.block_q = block_q
     self.block_kv = block_kv
     self.block_kv_compute = block_kv_compute if block_kv_compute is not None else block_kv