virtio: uapi: Drop __packed attribute in linux/virtio_pci.h

Commit 92792ac7 ("virtio-pci: Introduce admin command sending function")
added "__packed" structures to UAPI header linux/virtio_pci.h. This triggers
build failures in the consumer userspace applications without proper "definition"
of __packed (e.g., kvmtool build fails).

Moreover, the structures are already packed well, and doesn't need explicit
packing, similar to the rest of the structures in all virtio_* headers. Remove
the __packed attribute.

Fixes: 92792ac7 ("virtio-pci: Introduce admin command sending function")
Cc: Feng Liu <feliu@nvidia.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Yishai Hadas <yishaih@nvidia.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Jean-Philippe Brucker <jean-philippe@linaro.org>
Reviewed-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Message-Id: <20240125232039.913606-1-suzuki.poulose@arm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

include/uapi/linux/virtio_pci.h

@@ -240,7 +240,7 @@ struct virtio_pci_cfg_cap {
 #define VIRTIO_ADMIN_CMD_LEGACY_DEV_CFG_READ		0x5
 #define VIRTIO_ADMIN_CMD_LEGACY_NOTIFY_INFO		0x6
 
-struct __packed virtio_admin_cmd_hdr {
+struct virtio_admin_cmd_hdr {
 	__le16 opcode;
 	/*
 	 * 1 - SR-IOV
@@ -252,20 +252,20 @@ struct __packed virtio_admin_cmd_hdr {
 	__le64 group_member_id;
 };
 
-struct __packed virtio_admin_cmd_status {
+struct virtio_admin_cmd_status {
 	__le16 status;
 	__le16 status_qualifier;
 	/* Unused, reserved for future extensions. */
 	__u8 reserved2[4];
 };
 
-struct __packed virtio_admin_cmd_legacy_wr_data {
+struct virtio_admin_cmd_legacy_wr_data {
 	__u8 offset; /* Starting offset of the register(s) to write. */
 	__u8 reserved[7];
 	__u8 registers[];
 };
 
-struct __packed virtio_admin_cmd_legacy_rd_data {
+struct virtio_admin_cmd_legacy_rd_data {
 	__u8 offset; /* Starting offset of the register(s) to read. */
 };
 
@@ -275,7 +275,7 @@ struct __packed virtio_admin_cmd_legacy_rd_data {
 
 #define VIRTIO_ADMIN_CMD_MAX_NOTIFY_INFO 4
 
-struct __packed virtio_admin_cmd_notify_info_data {
+struct virtio_admin_cmd_notify_info_data {
 	__u8 flags; /* 0 = end of list, 1 = owner device, 2 = member device */
 	__u8 bar; /* BAR of the member or the owner device */
 	__u8 padding[6];