Drop usb buffering message to debug logging level.

usbutils.c

@@ -2491,7 +2491,7 @@ int _usb_read(struct cgpu_info *cgpu, int intinfo, int epinfo, char *buf, size_t
 			memcpy(usbdev->buffer, usbbuf + bufsiz, usbdev->bufamt);
 			tot -= usbdev->bufamt;
 			usbbuf[tot] = '\0';
-			applog(LOG_INFO, "USB: %s%i read1 buffering %d extra bytes",
+			applog(LOG_DEBUG, "USB: %s%i read1 buffering %d extra bytes",
 			       cgpu->drv->name, cgpu->device_id, usbdev->bufamt);
 		}
 
@@ -2615,7 +2615,7 @@ int _usb_read(struct cgpu_info *cgpu, int intinfo, int epinfo, char *buf, size_t
 			tot -= usbdev->bufamt;
 			memcpy(usbdev->buffer, usbbuf + tot, usbdev->bufamt);
 			usbbuf[tot] = '\0';
-			applog(LOG_ERR, "USB: %s%i read2 buffering %d extra bytes",
+			applog(LOG_DEBUG, "USB: %s%i read2 buffering %d extra bytes",
 			       cgpu->drv->name, cgpu->device_id, usbdev->bufamt);
 		}
 	}