Revert "net/http: Allow use of non-standard TCP/IP ports"

Revert "net/http: Allow use of non-standard TCP/IP ports"

The notation introduced in ac8a37dda (net/http: Allow use of non-standard
TCP/IP ports) contradicts that used in downstream distributions including
Fedora, RHEL, Debian, Ubuntu, and others. Revert it and apply the downstream
notation which was originally proposed to the GRUB in 2016.

This reverts commit ac8a37dda (net/http: Allow use of non-standard TCP/IP ports).

Signed-off-by: Robbie Harwood <rharwood@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>