drm/amd/amdgpu/amdgpu_psp: Make local function 'parse_ta_bin_descriptor' static

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

 drivers/gpu/drm/amd/amdgpu/amdgpu_psp.c:2576:5: warning: no previous prototype for ‘parse_ta_bin_descriptor’ [-Wmissing-prototypes]

Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: amd-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -2574,7 +2574,7 @@ int psp_init_sos_microcode(struct psp_context *psp,
 	return err;
 }
 
-int parse_ta_bin_descriptor(struct psp_context *psp,
+static int parse_ta_bin_descriptor(struct psp_context *psp,
 				   const struct ta_fw_bin_desc *desc,
 				   const struct ta_firmware_header_v2_0 *ta_hdr)
 {