next-20250623: riscv defconfig raid6 recov_rvv.c use of undeclared identifier 'raid6_empty_zero_page'

[Naresh Kamboju]

Regressions on riscv defconfig builds with gcc-13 and clang failed
on the Linux next-20250623 tag.

Regressions found on riscv
* riscv, build
  - clang-20-defconfig
  - gcc-13-defconfig
  - rustclang-nightly-lkftconfig-kselftest
  - rustgcc-lkftconfig-kselftest
  - rv32-clang-20-defconfig

Regression Analysis:
 - New regression? Yes
 - Reproducibility? Yes

Build regression: riscv defconfig raid6 recov_rvv.c use of undeclared
identifier 'raid6_empty_zero_page'

Reported-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx>

## Build log
lib/raid6/recov_rvv.c:168:24: error: use of undeclared identifier
'raid6_empty_zero_page'
  168 |         ptrs[faila] = (void *)raid6_empty_zero_page;
      |                               ^
/lib/raid6/recov_rvv.c:171:24: error: use of undeclared identifier
'raid6_empty_zero_page'
  171 |         ptrs[failb] = (void *)raid6_empty_zero_page;
      |                               ^
/lib/raid6/recov_rvv.c:206:24: error: use of undeclared identifier
'raid6_empty_zero_page'
  206 |         ptrs[faila] = (void *)raid6_empty_zero_page;
      |                               ^
3 errors generated.

## Source
* Kernel version: 6.16.0-rc3-next-20250623
* Git tree: https://kernel.googlesource.com/pub/scm/linux/kernel/git/next/linux-next.git
* Git sha: f817b6dd2b62d921a6cdc0a3ac599cd1851f343c
* Git describe: next-20250623
* Project details:
https://regressions.linaro.org/lkft/linux-next-master/next-20250623/
* Architectures: riscv
* Toolchains: gcc-13
* Kconfigs: defconfig

## Build arm64
* Build log: https://qa-reports.linaro.org/api/testruns/28829977/log_file/
* Build details:
https://regressions.linaro.org/lkft/linux-next-master/next-20250623/build/gcc-13-defconfig/
* Build link: https://storage.tuxsuite.com/public/linaro/lkft/builds/2ytmqfZ6v24dxq5kjorJbgH6hC8/
* Kernel config:
https://storage.tuxsuite.com/public/linaro/lkft/builds/2ytmqfZ6v24dxq5kjorJbgH6hC8/config

--
Linaro LKFT
https://lkft.linaro.org