strlcpy function is defined in uClibc library, causing "static
declaration of ‘strlcpy’ follows non-static declaration" build
errors.

Rename internal strlcpy function to DT_strlcpy to avoid conflicts.

Signed-off-by: Marcin Niestroj <m.niestroj@grinn-global.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>