net: stmmac: Add function to read pinctrl names

Add function to read pinctrl names.
Fix print for the logs to include line number.

Change-Id: I65e341c14104aabec77edcc79cdf97358648914c
Acked-by: Nagarjuna Chaganti <nchagant@qti.qualcomm.com>
Signed-off-by: Suraj Jaiswal <jsuraj@codeaurora.org>