drm/amd/amdgpu: Properly tune the size of struct

The struct assertion is failed because sparse cannot parse
`#pragma pack(push, 1)` and `#pragma pack(pop)` correctly.
GCC's output is still 1-byte-aligned. No harm to memory layout.

The error can be filtered out by sparse-diff, but sometimes
multiple lines queezed into one, making the sparse-diff thinks
its a new error. I'm trying to aviod this by fixing errors.

Link: https://lore.kernel.org/all/20230620045919.492128-1-suhui@nfschina.com/
Link: https://lore.kernel.org/all/93d10611-9fbb-4242-87b8-5860b2606042@suswa.mountain/
Fixes: 1721bc1b ("drm/amdgpu: Update VF2PF interface")
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Cc: wenlunpeng <wenlunpeng@uniontech.com>
Reported-by: Su Hui <suhui@nfschina.com>
Signed-off-by: WangYuli <wangyuli@uniontech.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -213,7 +213,7 @@ struct amd_sriov_msg_pf2vf_info {
 	uint32_t gpu_capacity;
 	/* reserved */
 	uint32_t reserved[256 - AMD_SRIOV_MSG_PF2VF_INFO_FILLED_SIZE];
-};
+} __packed;
 
 struct amd_sriov_msg_vf2pf_info_header {
 	/* the total structure size in byte */
@@ -273,7 +273,7 @@ struct amd_sriov_msg_vf2pf_info {
 	uint32_t mes_info_size;
 	/* reserved */
 	uint32_t reserved[256 - AMD_SRIOV_MSG_VF2PF_INFO_FILLED_SIZE];
-};
+} __packed;
 
 /* mailbox message send from guest to host  */
 enum amd_sriov_mailbox_request_message {