bus_blaster: do not fail on missing get_latency_timer

Patch submitted from Trac #64
Seems certain clones do not correctly emulate the ftdi chip, if
the call to read the latency timer fails then do not treat this as a
failure.

Change-Id: Iae671b926d101adf1010639d11ca46c58d0af524
Signed-off-by: Spencer Oliver <spen@spen-soft.co.uk>
Reviewed-on: http://openocd.zylin.com/1627


Tested-by: jenkins
Reviewed-by: Xiaofan <xiaofanc@gmail.com>

src/jtag/drivers/usb_blaster/ublast_access_ftd2xx.c

@@ -136,11 +136,10 @@ static int ublast_ftd2xx_init(struct ublast_lowlevel *low)
 	}
 
 	status = FT_GetLatencyTimer(*ftdih, &latency_timer);
-	if (status != FT_OK) {
+	if (status != FT_OK)
 		LOG_ERROR("unable to get latency timer: %s",
 				ftd2xx_status_string(status));
-		return ERROR_JTAG_INIT_FAILED;
-	}
+	else
 		LOG_DEBUG("current latency timer: %i", latency_timer);
 
 	status = FT_SetBitMode(*ftdih, 0x00, 0);

src/jtag/drivers/usb_blaster/ublast_access_ftdi.c

@@ -99,10 +99,9 @@ static int ublast_ftdi_init(struct ublast_lowlevel *low)
 		return ERROR_JTAG_INIT_FAILED;
 	}
 
-	if (ftdi_get_latency_timer(ftdic, &latency_timer) < 0) {
+	if (ftdi_get_latency_timer(ftdic, &latency_timer) < 0)
 		LOG_ERROR("unable to get latency timer");
-		return ERROR_JTAG_INIT_FAILED;
-	}
+	else
 		LOG_DEBUG("current latency timer: %u", latency_timer);
 
 	ftdi_disable_bitbang(ftdic);