Revert "genirq: assert that irq handlers are indeed running in hardirq context"

This reverts commit 044d4084.

The commit added a warning when handle_IRQ_event() is called outside
of hard interrupt context. This breaks the generic tasklet based
interrupt resend mechanism which is used when the hardware has no way
to retrigger the interrupt. So we get a warning for a use case which
is correct and worked for years. Remove it.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>