net: phylink: Fix phylink_dbg() macro

The phylink_dbg() macro does not follow dynamic debug or defined(DEBUG)
and as a result, it spams the kernel log since a PR_DEBUG level is
currently used. Fix it to be defined appropriately whether
CONFIG_DYNAMIC_DEBUG or defined(DEBUG) are set.

Fixes: 17091180 ("net: phylink: Add phylink_{printk, err, warn, info, dbg} macros")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>