Fix p_cols_fp32: use pv_mma_tiler[2] (K-dim) not [1] (N-dim)

dsv4/kernels/attention/fmha.py

@@ -346,7 +346,7 @@ class FmhaKernel:
 
             # ── P store setup (always define both paths — CuTeDSL scoping) ──
             # TMEM-P: register bridge for P → TMEM
-            p_cols_fp32 = self.pv_mma_tiler[1] * self.q_dtype.width // self.qk_acc_dtype.width
+            p_cols_fp32 = self.pv_mma_tiler[2] * self.q_dtype.width // self.qk_acc_dtype.width
             tStP_layout = cute.composition(tStS.layout, cute.make_layout((self.pv_mma_tiler[0], p_cols_fp32)))
             tStP0 = cute.make_tensor(tStS.iterator + self.tmem_p0_offset, tStP_layout)
             tmem_store_atom = cute.make_copy_atom(