irqchip/al-fic: make AL_FIC depend on HAS_IOMEM

On s390 systems (aka mainframes), it has classic channel devices for
networking and permanent storage that are currently even more common than
PCI devices.  Hence it could have a fully functional s390 kernel with
CONFIG_PCI=n, then the relevant iomem mapping functions [including
ioremap(), devm_ioremap(), etc.] are not available.

Here let AL_FIC depend on HAS_IOMEM so that it won't be built
to cause below compiling error if PCI is unset:

------
ld: drivers/irqchip/irq-al-fic.o: in function `al_fic_init_dt':
irq-al-fic.c:(.init.text+0x76): undefined reference to `of_iomap'
ld: irq-al-fic.c:(.init.text+0x4ce): undefined reference to `iounmap'
------

Link: https://lkml.kernel.org/r/20230707135852.24292-7-bhe@redhat.com
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202306211329.ticOJCSv-lkp@intel.com/
Signed-off-by: Baoquan He <bhe@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Marc Zyngier <maz@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>