net: tftpput: Support selecting get/put for tftp

TftpStart should support starting either a get or a put.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/net/bootp.c b/net/bootp.c
index 73470f2..b703f42 100644
--- a/net/bootp.c
+++ b/net/bootp.c
@@ -165,7 +165,7 @@
 		}
 #endif
 	}
-	TftpStart();
+	TftpStart(TFTPGET);
 }
 
 #if !defined(CONFIG_CMD_DHCP)