iproute: make clang happy

iproute: make clang happy

These are primarily fixes for "string is not string literal" warnings
/ errors (with -Werror -Wformat-nonliteral). This should be a no-op
change. I had to replace couple of print helper functions with the
code they call as it was becoming harder to eliminate these warnings,
however these helpers were used only at couple of places, so no
major change as such.

Signed-off-by: Mahesh Bandewar <maheshb@google.com>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>