Drop objid argument in zfs_znode_alloc() (sync with OpenZFS)

Drop objid argument in zfs_znode_alloc() (sync with OpenZFS)

Since zfs_znode_alloc() already takes dmu_buf_t*, taking another
uint64_t argument for objid is redundant. inode's ->i_ino does and
needs to match znode's ->z_id.

zfs_znode_alloc() in FreeBSD and illumos doesn't have this argument
since vnode doesn't have vnode# in VFS (hence ->z_id exists).

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Tomohiro Kusumi <kusumi.tomohiro@osnexus.com>
Closes #8841