ARM: 9047/1: smp: remove unused variable

Not used anymore after refactoring:

arch/arm/kernel/smp.c: In function ‘show_ipi_list’:
arch/arm/kernel/smp.c:543:16: warning: variable ‘irq’ set but not used [-Wunused-but-set-variable]
  543 |   unsigned int irq;

Fixes: 88c63774 ("ARM: smp: Use irq_desc_kstat_cpu() in show_ipi_list()")
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Marc Zyngier <maz@kernel.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>