Merge patch "Fix a segmentation fault also add raid6test for RISC-V support"

Merge patch "Fix a segmentation fault also add raid6test for RISC-V support"

This is a fix in the middle of a feature set, so I'm going to take the
fix onto fixes on its own.

* b4-shazam-merge:
  raid6: riscv: Fix NULL pointer dereference issue

Link: https://lore.kernel.org/r/20250610101234.1100660-1-zhangchunyan@iscas.ac.cn
Signed-off-by: Palmer Dabbelt <palmer@dabbelt.com>