irqchip/sg2042-msi: Fix wrong type cast in sg2044_msi_irq_ack()

irqchip/sg2042-msi: Fix wrong type cast in sg2044_msi_irq_ack()

The type cast in sg2044_msi_irq_ack() lost the __iomem attribute, which
makes the pointer type incorrect.

Add it back.

Fixes: e96b93a97c90 ("irqchip/sg2042-msi: Add the Sophgo SG2044 MSI interrupt controller")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Inochi Amaoto <inochiama@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Chen Wang <unicorn_wang@outlook.com>
Link: https://lore.kernel.org/all/20250422003804.214264-1-inochiama@gmail.com
Closes: https://lore.kernel.org/oe-kbuild-all/202504211251.B3aesulq-lkp@intel.com/