drm/amd/pm: add missing prototypes to amdgpu_dpm_internal

Include the header with the prototype to silence the following clang
warnings:

drivers/gpu/drm/amd/amdgpu/../pm/amdgpu_dpm_internal.c:29:6: warning: no
previous prototype for function 'amdgpu_dpm_get_active_displays'
[-Wmissing-prototypes]
void amdgpu_dpm_get_active_displays(struct amdgpu_device *adev)
     ^
drivers/gpu/drm/amd/amdgpu/../pm/amdgpu_dpm_internal.c:29:1: note: declare
'static' if the function is not intended to be used outside of this
translation unit
void amdgpu_dpm_get_active_displays(struct amdgpu_device *adev)
^
static
drivers/gpu/drm/amd/amdgpu/../pm/amdgpu_dpm_internal.c:76:5: warning: no
previous prototype for function 'amdgpu_dpm_get_vrefresh'
[-Wmissing-prototypes]
u32 amdgpu_dpm_get_vrefresh(struct amdgpu_device *adev)
    ^
drivers/gpu/drm/amd/amdgpu/../pm/amdgpu_dpm_internal.c:76:1: note: declare
'static' if the function is not intended to be used outside of this
translation unit
u32 amdgpu_dpm_get_vrefresh(struct amdgpu_device *adev)
^
static
2 warnings generated.

Besides that, remove the duplicated prototype of the function
amdgpu_dpm_get_vblank_time in order to keep the consistency of the
headers.

Fixes: 6ddbd37f ("drm/amd/pm: optimize the amdgpu_pm_compute_clocks() implementations")
Reviewed-by: Evan Quan <evan.quan@amd.com>
Signed-off-by: Maíra Canal <maira.canal@usp.br>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/pm/amdgpu_dpm_internal.c

@@ -25,6 +25,7 @@
 #include "amdgpu_display.h"
 #include "hwmgr.h"
 #include "amdgpu_smu.h"
+#include "amdgpu_dpm_internal.h"
 
 void amdgpu_dpm_get_active_displays(struct amdgpu_device *adev)
 {

drivers/gpu/drm/amd/pm/inc/amdgpu_dpm.h

@@ -343,7 +343,6 @@ struct amdgpu_pm {
 	struct amdgpu_ctx       *stable_pstate_ctx;
 };
 
-u32 amdgpu_dpm_get_vblank_time(struct amdgpu_device *adev);
 int amdgpu_dpm_read_sensor(struct amdgpu_device *adev, enum amd_pp_sensors sensor,
 			   void *data, uint32_t *size);
 

drivers/gpu/drm/amd/pm/legacy-dpm/si_dpm.c

@@ -28,6 +28,7 @@
 #include "amdgpu_pm.h"
 #include "amdgpu_dpm.h"
 #include "amdgpu_atombios.h"
+#include "amdgpu_dpm_internal.h"
 #include "amd_pcie.h"
 #include "sid.h"
 #include "r600_dpm.h"