drm/amdgpu: Fix missing prototype warning

Fix a missing prototype warning for function
amdgpu_info_ioctl(),

drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c:482:5: warning: no previous prototype for 'amdgpu_info_ioctl' [-Wmissing-prototypes]
Signed-off-by: NLuben Tuikov <luben.tuikov@amd.com>
Reported-by: Nkernel test robot <lkp@intel.com>
Reviewed-by: NSouptick Joarder <jrdr.linux@gmail.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201110051548.685725-1-luben.tuikov@amd.com

drivers/gpu/drm/amd/amdgpu/amdgpu.h

@@ -1276,6 +1276,8 @@ int amdgpu_enable_vblank_kms(struct drm_crtc *crtc);
 void amdgpu_disable_vblank_kms(struct drm_crtc *crtc);
 long amdgpu_kms_compat_ioctl(struct file *filp, unsigned int cmd,
 			     unsigned long arg);
+int amdgpu_info_ioctl(struct drm_device *dev, void *data,
+		      struct drm_file *filp);
 
 /*
  * functions used by amdgpu_encoder.c

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

@@ -1521,8 +1521,6 @@ int amdgpu_file_to_fpriv(struct file *filp, struct amdgpu_fpriv **fpriv)
 	return 0;
 }
 
-int amdgpu_info_ioctl(struct drm_device *dev, void *data, struct drm_file *filp);
-
 const struct drm_ioctl_desc amdgpu_ioctls_kms[] = {
 	DRM_IOCTL_DEF_DRV(AMDGPU_GEM_CREATE, amdgpu_gem_create_ioctl, DRM_AUTH|DRM_RENDER_ALLOW),
 	DRM_IOCTL_DEF_DRV(AMDGPU_CTX, amdgpu_ctx_ioctl, DRM_AUTH|DRM_RENDER_ALLOW),