drm/amdgpu: make program_imu_rlc_ram static

This symbol is not used outside of imu_v11_0.c, so marks it
static.

Fixes the following w1 warning:

drivers/gpu/drm/amd/amdgpu/imu_v11_0.c:302:6: warning: no previous
prototype for ‘program_imu_rlc_ram’ [-Wmissing-prototypes].
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/imu_v11_0.c

@@ -299,7 +299,7 @@ static const struct imu_rlc_ram_golden imu_rlc_ram_golden_11_0_2[] =
 	IMU_RLC_RAM_GOLDEN_VALUE(GC, 0, regCPG_PSP_DEBUG, CPG_PSP_DEBUG__GPA_OVERRIDE_MASK, 0)
 };
 
-void program_imu_rlc_ram(struct amdgpu_device *adev,
+static void program_imu_rlc_ram(struct amdgpu_device *adev,
 				const struct imu_rlc_ram_golden *regs,
 				const u32 array_size)
 {