lib/rhashtable: fix the typo for preemptible

Fix the spelling of the mis-spelled word

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Pratyush Mittal <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

lib/rhashtable.c

···
  * structure outside the hash table.
  *
  * This function may be called from any process context, including
- * non-preemptable context, but cannot be called from softirq or
+ * non-preemptible context, but cannot be called from softirq or
  * hardirq context.
  *
  * You must call rhashtable_walk_exit after this function returns.