arm64: replace in_irq() with in_hardirq()

Replace the obsolete and ambiguos macro in_irq() with new
macro in_hardirq().

Signed-off-by: Changbin Du <changbin.du@gmail.com>
Link: https://lore.kernel.org/r/20210814005405.2658-1-changbin.du@gmail.com


Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>