panvk: Remove duplicate variable src_idx
What does this MR do and why?
panvk: Remove duplicate variable src_idx
Fix defect reported by Coverity Scan.
Evaluation order violation (EVALUATION_ORDER)
write_write_typo: In src_idx = src_idx = binding_layout->desc_idx + i * desc_stride + subdesc_idx,
src_idx is written twice with the same value.
Fixes: 7bea6f8612e1 ("panvk: Overhaul the Bifrost descriptor set implementation")
Signed-off-by: Vinson Lee <vlee@freedesktop.org>