Revert "arc_evict, arc_evict_ghost: reduce stack usage using kmem_zalloc"

This reverts commit 16fcdea36340c658b4557fd34a74915fd618f7a6 in preparation
for the illumos 5497 "lock contention on arcs_mtx" patch which eliminates
"marker" within the ARC code.

Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>