drm/xe: make hwmon_info const

Make hwmon_info a const array of const pointers, and let it be placed in
rodata.

Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240117122044.1544174-3-jani.nikula@intel.com


Signed-off-by: Jani Nikula <jani.nikula@intel.com>