dediprog: fix SPI clock setting

Avoid setting SPI speed on firmware versions < 5.0.0 and note this
limitation in the man page.
Use the correct offset of the "12M" element in the spispeeds array to
match our manpage and the default of Dediprog's dpcmd.

Corresponding to flashrom svn r1674.

Signed-off-by: Patrick Georgi <patrick.georgi@secunet.com>
Signed-off-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
Acked-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
diff --git a/dediprog.c b/dediprog.c
index ab5388b..fb95d10 100644
--- a/dediprog.c
+++ b/dediprog.c
@@ -184,12 +184,15 @@
  */
 static int dediprog_set_spi_speed(unsigned int spispeed_idx)
 {
-	int ret;
+	if (dediprog_firmwareversion < FIRMWARE_VERSION(5, 0, 0)) {
+		msg_pwarn("Skipping to set SPI speed because firmware is too old.\n");
+		return 0;
+	}
 
-	msg_pdbg("SPI speed is %sHz\n", spispeeds[spispeed_idx].name);
+	msg_pdbg("SPI speed is %s Hz\n", spispeeds[spispeed_idx].name);
 
-	ret = usb_control_msg(dediprog_handle, 0x42, 0x61, spispeeds[spispeed_idx].speed, 0xff,
-			      NULL, 0x0, DEFAULT_TIMEOUT);
+	int ret = usb_control_msg(dediprog_handle, 0x42, 0x61, spispeeds[spispeed_idx].speed, 0xff,
+				  NULL, 0x0, DEFAULT_TIMEOUT);
 	if (ret != 0x0) {
 		msg_perr("Command Set SPI Speed 0x%x failed!\n", spispeeds[spispeed_idx].speed);
 		return 1;
@@ -789,7 +792,7 @@
 {
 	struct usb_device *dev;
 	char *voltage, *device, *spispeed, *target_str;
-	int spispeed_idx = 2;
+	int spispeed_idx = 1;
 	int millivolt = 3500;
 	long usedevice = 0;
 	long target = 1;
@@ -806,7 +809,7 @@
 			}
 		}
 		if (!spispeeds[i].name) {
-			msg_perr("Error: Invalid 'spispeed' value.\n");
+			msg_perr("Error: Invalid spispeed value: '%s'.\n", spispeed);
 			free(spispeed);
 			return 1;
 		}