iommu/dart: Remove iommu_flush_ops

iommu/dart: Remove iommu_flush_ops

apple_dart_tlb_flush_{all,walk} expect to get a struct apple_dart_domain
but instead get a struct iommu_domain right now. This breaks those two
functions and can lead to kernel panics like the one below.
DART can only invalidate the entire TLB and apple_dart_iotlb_sync will
already flush everything. There's no need to do that again inside those
two functions. Let's just drop them.

  pci 0000:03:00.0: Removing from iommu group 1
  Unable to handle kernel paging request at virtual address 0000000100000023
  [...]
  Call trace:
   _raw_spin_lock_irqsave+0x54/0xbc
   apple_dart_hw_stream_command.constprop.0+0x2c/0x130
   apple_dart_tlb_flush_all+0x48/0x90
   free_io_pgtable_ops+0x40/0x70
   apple_dart_domain_free+0x2c/0x44
   iommu_group_release+0x68/0xac
   kobject_cleanup+0x4c/0x1fc
   kobject_cleanup+0x14c/0x1fc
   kobject_put+0x64/0x84
   iommu_group_remove_device+0x110/0x180
   iommu_release_device+0x50/0xa0
  [...]

Fixes: 46d1fb072e76b161 ("iommu/dart: Add DART iommu driver")
Reported-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Sven Peter <sven@svenpeter.dev>
Acked-by: Marc Zyngier <maz@kernel.org>
Tested-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210921153934.35647-1-sven@svenpeter.dev
Signed-off-by: Joerg Roedel <jroedel@suse.de>