intel/compiler: initialize remaining fields of various classes

These variables seem to be initialized before being used, so this
patch is not fixing any bug, but leaving them unitialized may become
a bug after some refactoring.

These classes were affected: fs_reg_alloc, fs_visitor, fs_generator,
instruction_scheduler.

Found by Coverity.

Signed-off-by: Marcin Ślusarz <marcin.slusarz@intel.com>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6667>
4 files changed