ipaddress: Make print_linkinfo_brief() static

ipaddress: Make print_linkinfo_brief() static

It shares lot of code with print_linkinfo(): drop duplicated part,
change parameters list, make it static and call from print_linkinfo()
after common path.

While there move SPRINT_BUF() to the function scope from blocks to
avoid duplication and use "%s" to print "\n" to help compiler optimize
exit for both print_linkinfo_brief() and normal paths.

Signed-off-by: Serhey Popovych <serhe.popovych@gmail.com>
Signed-off-by: David Ahern <dsahern@gmail.com>