soundwire: bus: Make IRQ handling conditionally built

soundwire: bus: Make IRQ handling conditionally built

SoundWire has provisions for a simple callback for the IRQ handling so
has no hard dependency on IRQ_DOMAIN, but the recent addition of IRQ
handling was causing builds without IRQ_DOMAIN to fail. Resolve this by
moving the IRQ handling into its own file and only add it to the build
when IRQ_DOMAIN is included in the kernel.

Fixes: 12a95123bfe1 ("soundwire: bus: Allow SoundWire peripherals to register IRQ handlers")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202309150522.MoKeF4jx-lkp@intel.com/
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20230920160401.854052-1-ckeepax@opensource.cirrus.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>