drm/amd/amdgpu/dce_v6_0: Repair function name of 'si_get_number_of_dram_channels()'

Fixes the following W=1 kernel build warning(s):

drivers/gpu/drm/amd/amdgpu/dce_v6_0.c:468: warning: expecting prototype for cik_get_number_of_dram_channels(). Prototype was for si_get_number_of_dram_channels() instead

Cc: Alex Deucher <[e-mail]>
Cc: "Christian König" <[e-mail]>
Cc: David Airlie <[e-mail]>
Cc: Daniel Vetter <[e-mail]>
Cc: Luben Tuikov <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Signed-off-by: Lee Jones <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/amdgpu/dce_v6_0.c

···
 }
 
 /**
- * cik_get_number_of_dram_channels - get the number of dram channels
+ * si_get_number_of_dram_channels - get the number of dram channels
  *
  * @adev: amdgpu_device pointer
  *