core_alua_check_nonop_delay() uses in_interrupt() to decide if it is safe
to sleep.

The usage of in_interrupt() in drivers is phased out and Linus clearly
requested that code which changes behaviour depending on context should
either be separated or the context be conveyed in an argument passed by the
caller, which usually knows the context.

core_alua_check_nonop_delay() has two callers:

 - target_submit_cmd_map_sgls()
   Kernel doc says it that it must be called from process context. Also has
   a BUG_ON(in_interrupt()).

 - iscsit_setup_scsi_cmd()
   Invokes iscsit_add_reject_cmd() which does GFP_KERNEL allocation and
   target_cmd_init_cdb() which may do GFP_KERNEL allocations.

Remove the in_interrupt() check because all callers are from preemptible
context.

Link: https://lore.kernel.org/r/20201220203638.43615-5-bigeasy@linutronix.deSigned-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>