simd_stat: fix undefined CONFIG_KERNEL_MODE_NEON error on armel

[Harry-Chen]

Motivation and Context

Currently zfs 2.2.7 / 2.3.0-rc4 / master won't compile on armel.

See debian buildd log:

525s /tmp/autopkgtest-lxc.ai7b0w_k/downtmp/build.TuL/src/module/zcommon/simd_stat.c: In function ‘simd_stat_kstat_data’:
525s /tmp/autopkgtest-lxc.ai7b0w_k/downtmp/build.TuL/src/module/zcommon/simd_stat.c:136:41: error: ‘CONFIG_KERNEL_MODE_NEON’ undeclared (first use in this function)
525s   136 |                     "kernel_mode_neon", CONFIG_KERNEL_MODE_NEON);
525s       |                                         ^~~~~~~~~~~~~~~~~~~~~~~
525s /tmp/autopkgtest-lxc.ai7b0w_k/downtmp/build.TuL/src/module/zcommon/simd_stat.c:52:74: note: in definition of macro ‘SIMD_STAT_PRINT’
525s    52 |         kmem_scnprintf(s + off, MAX(4095-off, 0), "%-16s\t%1d\n", feat, (val))
525s       |                                                                          ^~~
525s /tmp/autopkgtest-lxc.ai7b0w_k/downtmp/build.TuL/src/module/zcommon/simd_stat.c:136:41: note: each undeclared identifier is reported only once for each function it appears in
525s   136 |                     "kernel_mode_neon", CONFIG_KERNEL_MODE_NEON);
525s       |                                         ^~~~~~~~~~~~~~~~~~~~~~~
525s /tmp/autopkgtest-lxc.ai7b0w_k/downtmp/build.TuL/src/module/zcommon/simd_stat.c:52:74: note: in definition of macro ‘SIMD_STAT_PRINT’
525s    52 |         kmem_scnprintf(s + off, MAX(4095-off, 0), "%-16s\t%1d\n", feat, (val))
525s       |                                                                          ^~~
525s make[4]: *** [/usr/src/linux-headers-6.11.10-common/scripts/Makefile.build:249: /tmp/autopkgtest-lxc.ai7b0w_k/downtmp/build.TuL/src/module/zcommon/simd_stat.o] Error 1

Description

CONFIG_KERNEL_MODE_NEON depends on CONFIG_NEON. Neither is defined on armel. So a guard is needed to avoid compilation errors.

How Has This Been Tested?

It now compiles. Should not affect any other functionalities.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Performance enhancement (non-breaking change which improves efficiency)
• Code cleanup (non-breaking change which makes code smaller or more readable)
• Breaking change (fix or feature that would cause existing functionality to change)
• Library ABI change (libzfs, libzfs_core, libnvpair, libuutil and libzfsbootenv)
• Documentation (a change to man pages or other documentation)

Checklist:

• My code follows the OpenZFS code style requirements.
• I have updated the documentation accordingly.
• I have read the contributing document.
• I have added tests to cover my changes.
• I have run the ZFS Test Suite with this change applied.
• All commit messages are properly formatted and contain Signed-off-by.

[behlendorf]

Thanks!