irqchip/gic-v5: Remove undue WARN_ON()s in the IRS affinity parsing

irqchip/gic-v5: Remove undue WARN_ON()s in the IRS affinity parsing

In gicv5_irs_of_init_affinity() a WARN_ON() is triggered if:

 1) a phandle in the "cpus" property does not correspond to a valid OF
    node
 2  a CPU logical id does not exist for a given OF cpu_node

#1 is a firmware bug and should be reported as such but does not warrant a
   WARN_ON() backtrace.

#2 is not necessarily an error condition (eg a kernel can be booted with
   nr_cpus=X limiting the number of cores artificially) and therefore there
   is no reason to clutter the kernel log with WARN_ON() output when the
   condition is hit.

Rework the IRS affinity parsing code to remove undue WARN_ON()s thus
making it less noisy.

Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250814094138.1611017-1-lpieralisi@kernel.org