vsock: use sizeof(struct sockaddr_storage) instead of magic value

vsock: use sizeof(struct sockaddr_storage) instead of magic value

Previous commit 230b183921ec ("net: Use standard structures for generic
socket address structures.") use 'struct sockaddr_storage address;'
to replace 'char address[MAX_SOCK_ADDR];'.

The macro MAX_SOCK_ADDR is removed by commit 01893c82b4e6 ("net: Remove
MAX_SOCK_ADDR constant").

The comment in vsock_getname() is outdated, use sizeof(struct
sockaddr_storage) instead of magic value 128.

Signed-off-by: Wang Liang <wangliang74@huawei.com>
Link: https://patch.msgid.link/20250812015929.1419896-1-wangliang74@huawei.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>