vfs: Fix resource leaks in kern_symlinkat()

Fixes: 2ec2ba7e232d ("vfs: Add VFS/syscall support for Solaris style extended attributes")
Reported by: Yuxiang Yang, Yizhou Zhao, Ao Wang, Xuewei Feng, Qi Li,

		and Ke Xu from Tsinghua University using GLM-5.2 from Z.ai

Reviewed by: rmacklem, kib
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D58053