drm/amdgpu: remove redundant assignment to pointer write_frame

The pointer write_frame is being initialized with a value that is
never read and it is being updated later with a new value. The
initialization is redundant and can be removed.

Addresses-Coverity: ("Unused value")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -1728,7 +1728,7 @@ int psp_ring_cmd_submit(struct psp_context *psp,
 			int index)
 {
 	unsigned int psp_write_ptr_reg = 0;
-	struct psp_gfx_rb_frame *write_frame = psp->km_ring.ring_mem;
+	struct psp_gfx_rb_frame *write_frame;
 	struct psp_ring *ring = &psp->km_ring;
 	struct psp_gfx_rb_frame *ring_buffer_start = ring->ring_mem;
 	struct psp_gfx_rb_frame *ring_buffer_end = ring_buffer_start +