doc: net: napi: Update documentation for napi_schedule_irqoff

Since commit 8380c81 ("net: Treat __napi_schedule_irqoff() as
__napi_schedule() on PREEMPT_RT"), napi_schedule_irqoff will do the
right thing if IRQs are threaded. Therefore, there is no need to use
IRQF_NO_THREAD.

Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/20240930153955.971657-1-sean.anderson@linux.dev
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Author: Sean Anderson

Documentation/networking/napi.rst

@@ -144,9 +144,8 @@ IRQ should only be unmasked after a successful call to napi_complete_done():
 
 napi_schedule_irqoff() is a variant of napi_schedule() which takes advantage
 of guarantees given by being invoked in IRQ context (no need to
-mask interrupts). Note that PREEMPT_RT forces all interrupts
-to be threaded so the interrupt may need to be marked ``IRQF_NO_THREAD``
-to avoid issues on real-time kernel configurations.
+mask interrupts). napi_schedule_irqoff() will fall back to napi_schedule() if
+IRQs are threaded (such as if ``PREEMPT_RT`` is enabled).
 
 Instance to queue mapping
 -------------------------