nfs/localio: use read_seqbegin() rather than read_seqbegin_or_lock()

nfs/localio: use read_seqbegin() rather than read_seqbegin_or_lock()

The usage of read_seqbegin_or_lock() in nfs_copy_boot_verifier()
is wrong. "seq" is always even and thus "or_lock" has no effect.

nfs_copy_boot_verifier() just copies 8 bytes and is supposed to be
very rare operation, so we do not need the adaptive locking in this case.

Signed-off-by: Li RongQing <lirongqing@baidu.com>
Link: https://lore.kernel.org/r/20250731081038.3478-1-lirongqing@baidu.com
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>