lightnvm: Convert timers to use timer_setup()

In preparation for unconditionally passing the struct timer_list pointer to
all timer callbacks, switch to using the new timer_setup() and from_timer()
to pass the timer pointer explicitly.

Cc: Matias Bjorling <mb@lightnvm.io>
Cc: linux-block@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>

drivers/lightnvm/pblk.h

@@ -797,7 +797,7 @@ void pblk_map_rq(struct pblk *pblk, struct nvm_rq *rqd, unsigned int sentry,
  * pblk write thread
  */
 int pblk_write_ts(void *data);
-void pblk_write_timer_fn(unsigned long data);
+void pblk_write_timer_fn(struct timer_list *t);
 void pblk_write_should_kick(struct pblk *pblk);
 
 /*