drm/amdkfd: Fix kdoc entry for 'get_wave_count()' function parameters

Update kdoc entries to reflect the function's parameters. The descriptor
for the 'queue_cnt' parameter has been added, and the incorrect mentions
of 'wave_cnt' and 'vmid', which are not parameters but local variables,
have been removed.

Fixes the below with gcc W=1:
drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v9.c:954: warning: Function parameter or struct member 'queue_cnt' not described in 'get_wave_count'
drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v9.c:954: warning: Excess function parameter 'wave_cnt' description in 'get_wave_count'
drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v9.c:954: warning: Excess function parameter 'vmid' description in 'get_wave_count'

Cc: Ramesh Errabolu <Ramesh.Errabolu@amd.com>
Cc: Harish Kasiviswanathan <Harish.Kasiviswanathan@amd.com>
Cc: Felix Kuehling <felix.kuehling@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@amd.com>
Reviewed-by: Mukul Joshi <mukul.joshi@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>