net: cosmetic: Clean up DNS variables and functions

Make a thorough pass through all variables and function names contained
within dns.c and remove CamelCase and improve naming.

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/net/net.c b/net/net.c
index 3c8b608..1133f79 100644
--- a/net/net.c
+++ b/net/net.c
@@ -427,7 +427,7 @@
 #endif
 #if defined(CONFIG_CMD_DNS)
 		case DNS:
-			DnsStart();
+			dns_start();
 			break;
 #endif
 #if defined(CONFIG_CMD_LINK_LOCAL)