AMD KFD: Use fallthrough;

Convert the various uses of fallthrough comments to fallthrough;

Done via script
Link: https://lore.kernel.org/lkml/b56602fcf79f849e733e7b521bb0e17895d390fa.1582230379.git.joe@perches.com/Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -79,7 +79,7 @@ static uint32_t get_sdma_rlc_reg_offset(struct amdgpu_device *adev,
 		dev_warn(adev->dev,
 			 "Invalid sdma engine id (%d), using engine id 0\n",
 			 engine_id);
-		/* fall through */
+		fallthrough;
 	case 0:
 		sdma_engine_reg_base = SOC15_REG_OFFSET(SDMA0, 0,
 				mmSDMA0_RLC0_RB_CNTL) - mmSDMA0_RLC0_RB_CNTL;