mimxrt/tusb_config.h: Preliminary fix for TinyUSB HS endpoint overflow.

Sending more than 64 bytes to the USB CDC endpoint in HS mode will lead to
a hard crash.  This commit fixes the issue, although there may be a better
fix from upstream TinyUSB in the future.

ports/mimxrt/tusb_config.h

@@ -30,7 +30,8 @@
 #define CFG_TUSB_OS             (OPT_OS_NONE)
 
 #define CFG_TUD_CDC             (1)
-#define CFG_TUD_CDC_RX_BUFSIZE  (256)
-#define CFG_TUD_CDC_TX_BUFSIZE  (256)
+#define CFG_TUD_CDC_RX_BUFSIZE  (512)
+#define CFG_TUD_CDC_TX_BUFSIZE  (512)
+#define CFG_TUD_CDC_EPSIZE      (512)
 
 #endif // MICROPY_INCLUDED_MIMXRT_TUSB_CONFIG_H