USB: host: isp1362: delete isp1362_show_regs()

USB: host: isp1362: delete isp1362_show_regs()

No one is calling this function, so it's pointless to keep around as it
is triggering automated scanning tools to try to fix up the problems
with it using in_interrupt().

So delete the thing.

Reported-by: Thomas Gleixner <tglx@linutronix.de>
Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reported-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/20201028113107.2007742-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>