drm/amd/amdgpu: Add function prototypes to headers

Add function prototypes to headers to reduce the number of
-Wmissing-prototypes warnings.
Signed-off-by: Arthur Grillo <arthurgrillo@riseup.net>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -538,6 +538,7 @@ struct amdgpu_firmware {
 
 void amdgpu_ucode_print_mc_hdr(const struct common_firmware_header *hdr);
 void amdgpu_ucode_print_smc_hdr(const struct common_firmware_header *hdr);
+void amdgpu_ucode_print_imu_hdr(const struct common_firmware_header *hdr);
 void amdgpu_ucode_print_gfx_hdr(const struct common_firmware_header *hdr);
 void amdgpu_ucode_print_rlc_hdr(const struct common_firmware_header *hdr);
 void amdgpu_ucode_print_sdma_hdr(const struct common_firmware_header *hdr);