drm/amd/amdgpu: skip ucode loading if ucode_size == 0

stable inclusion
from stable-v5.10.144
commit 187908079d94673b01fbd63d7251bfab4341e7cb
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I6D0V7

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=187908079d94673b01fbd63d7251bfab4341e7cb



--------------------------------

[ Upstream commit 39c84b8e ]

Restrict the ucode loading check to avoid frontdoor loading error.

Signed-off-by: Chengming Gui <Jack.Gui@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com>
Reviewed-by: Zheng Zengkai <zhengzengkai@huawei.com>