board/common: Add convenience macros 'hd' and 'llping'

'hd':
    Hexdump, in canonical format

'llping':
    Ping any IPv6 neighbors using the link-local all-nodes group

    Usage: llping <IFACE>

board/common/rootfs/etc/profile.d/convenience.sh

@@ -11,6 +11,7 @@ alias view='vi -R'
 alias emacs='mg'
 alias sensible-editor=edit
 alias sensible-pager=pager
+alias hd="hexdump -C"
 
 alias ip='ip --color=auto'
 alias ipb='ip -br'
@@ -18,4 +19,6 @@ alias ipaddr='ip addr'
 alias iplink='ip link'
 alias bridge='bridge --color=auto'
 
+alias llping='ping -L ff02::1 -I'
+
 alias docker=podman