soc: ti: ti_sci_inta_msi: Remove ti_sci_inta_msi_domain_free_irqs()

The function has no users and is pointless now that the core frees the MSI
descriptors, which means potential users can just use msi_domain_free_irqs().

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nishanth Menon <nm@ti.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20211206210748.793119155@linutronix.de