xtensa: remove NO_IRQ definitions

These definitions (-1) were correct when used as a hardware IRQ number,
but are incorrect as a mapped IRQ number.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>

diff --cc arch/xtensa/platforms/xtfpga/include/platform/hardware.h
Simple merge

diff --cc arch/xtensa/variants/s6000/include/variant/irq.h
Simple merge