irqchip/aspeed-scu-ic: Remove unused variable mask

irqchip/aspeed-scu-ic: Remove unused variable mask

The kernel test robot reports:

  drivers/irqchip/irq-aspeed-scu-ic.c:107:27: warning: variable 'mask' set but not used
     107 |         unsigned int sts, mask;

Remove the leftover.

Fixes: b2a0c13f8b4f ("irqchip/aspeed-scu-ic: Add support for AST2700 SCU interrupt controllers")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/874io0h3sz.ffs@tglx
Closes: https://lore.kernel.org/oe-kbuild-all/202602010957.9uuKqUkG-lkp@intel.com/