Convert CONFIG_PHY_RESET_DELAY to Kconfig

This converts the following to Kconfig:
   CONFIG_PHY_RESET_DELAY

Cc: Ramon Fried <rfried.dev@gmail.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
index fffa10f..92fff5b 100644
--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -872,7 +872,7 @@
 		return -1;
 	}
 
-#ifdef CONFIG_PHY_RESET_DELAY
+#if CONFIG_PHY_RESET_DELAY > 0
 	udelay(CONFIG_PHY_RESET_DELAY);	/* Intel LXT971A needs this */
 #endif
 	/*