Save 448 bytes of RAM with smaller buffer

Reduce the disk buffer size to 64 bytes.  The buffer is statically
allocated so it's always present, even in non-USB disk mode, meaning
all apps will pay the RAM price for it.  64 bytes is slower to read
but works and saves ~1/2KB of heap for all apps.

Author: earlephilhower

include/tusb_config.h

@@ -79,8 +79,7 @@
 #define CFG_TUD_CDC_RX_BUFSIZE  (256)
 #define CFG_TUD_CDC_TX_BUFSIZE  (256)
 
-#define CFG_TUD_MSC_EP_BUFSIZE  (512)
-
+#define CFG_TUD_MSC_EP_BUFSIZE  (64)
 
 // HID buffer size Should be sufficient to hold ID (if any) + Data
 #define CFG_TUD_HID_EP_BUFSIZE  (64)

lib/libpico-ipv6.a

@@ -79,8 +79,7 @@
 #define CFG_TUD_CDC_RX_BUFSIZE  (256)
 #define CFG_TUD_CDC_TX_BUFSIZE  (256)
 
-#define CFG_TUD_MSC_EP_BUFSIZE  (512)
-
+#define CFG_TUD_MSC_EP_BUFSIZE  (64)
 
 // HID buffer size Should be sufficient to hold ID (if any) + Data
 #define CFG_TUD_HID_EP_BUFSIZE  (64)