net: cosmetic: Clean up SNTP variables and functions

Make a thorough pass through all variables and function names contained
within sntp.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/sntp.h b/net/sntp.h
index bf5bf0b..6a9c6bb 100644
--- a/net/sntp.h
+++ b/net/sntp.h
@@ -53,6 +53,6 @@
 	unsigned long long transmit_timestamp;
 };
 
-extern void SntpStart(void);	/* Begin SNTP */
+void sntp_start(void);	/* Begin SNTP */
 
 #endif /* __SNTP_H__ */