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/common/miiphyutil.c b/common/miiphyutil.c
index 7d4d15e..194c84e 100644
--- a/common/miiphyutil.c
+++ b/common/miiphyutil.c
@@ -366,7 +366,7 @@
 		debug("PHY reset failed\n");
 		return -1;
 	}
-#ifdef CONFIG_PHY_RESET_DELAY
+#if CONFIG_PHY_RESET_DELAY > 0
 	udelay(CONFIG_PHY_RESET_DELAY);	/* Intel LXT971A needs this */
 #endif
 	/*