drm/amdgpu: fix warning about missing imu prototype

for imu_v11_0_3_program_rlc_ram(). Include imu_v11_0_3.h
in imu_v11_0_3.c.

Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>