drm/amdkfd: Fix unaligned 64-bit doorbell warning

drm/amdkfd: Fix unaligned 64-bit doorbell warning

This patch fixes the following unaligned 64-bit doorbell
warning seen when submitting packets on HIQ on GFX v9.4.3
by making the HIQ doorbell 64-bit aligned.
The warning is seen when GPU is loaded in any mode other
than SPX mode.

[  +0.000301] ------------[ cut here ]------------
[  +0.000003] Unaligned 64-bit doorbell
[  +0.000030] WARNING: /amdkfd/kfd_doorbell.c:339 write_kernel_doorbell64+0x72/0x80
[  +0.000003] RIP: 0010:write_kernel_doorbell64+0x72/0x80
[  +0.000004] RSP: 0018:ffffc90004287730 EFLAGS: 00010246
[  +0.000005] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[  +0.000003] RDX: 0000000000000001 RSI: ffffffff82837c71 RDI: 00000000ffffffff
[  +0.000003] RBP: ffffc90004287748 R08: 0000000000000003 R09: 0000000000000001
[  +0.000002] R10: 000000000000001a R11: ffff88a034008198 R12: ffffc900013bd004
[  +0.000003] R13: 0000000000000008 R14: ffffc900042877b0 R15: 000000000000007f
[  +0.000003] FS:  00007fa8c7b62000(0000) GS:ffff889f88400000(0000) knlGS:0000000000000000
[  +0.000004] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  +0.000003] CR2: 000056111c45aaf0 CR3: 00000001414f2002 CR4: 0000000000770ee0
[  +0.000003] PKRU: 55555554
[  +0.000002] Call Trace:
[  +0.000004]  <TASK>
[  +0.000006]  kq_submit_packet+0x45/0x50 [amdgpu]
[  +0.000524]  pm_send_set_resources+0x7f/0xc0 [amdgpu]
[  +0.000500]  set_sched_resources+0xe4/0x160 [amdgpu]
[  +0.000503]  start_cpsch+0x1c5/0x2a0 [amdgpu]
[  +0.000497]  kgd2kfd_device_init.cold+0x816/0xb42 [amdgpu]
[  +0.000743]  amdgpu_amdkfd_device_init+0x15f/0x1f0 [amdgpu]
[  +0.000602]  amdgpu_device_init.cold+0x1813/0x2176 [amdgpu]
[  +0.000684]  ? pci_bus_read_config_word+0x4a/0x80
[  +0.000012]  ? do_pci_enable_device+0xdc/0x110
[  +0.000008]  amdgpu_driver_load_kms+0x1a/0x110 [amdgpu]
[  +0.000545]  amdgpu_pci_probe+0x197/0x400 [amdgpu]

Fixes: c31866651086 ("drm/amdgpu: use doorbell mgr for kfd kernel doorbells")
Signed-off-by: Mukul Joshi <mukul.joshi@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>