um: vector: Use mac_pton() for MAC address parsing

Use mac_pton() instead of custom approach.

Suggested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Link: https://patch.msgid.link/20250506045117.1896661-3-tiwei.btw@antgroup.com


Signed-off-by: Johannes Berg <johannes.berg@intel.com>