fix(usb): Reset the watchdog while perfoming MSC operations

The MSC interrupts can come in back to back, effectively blocking
the FreeRTOS timer task which resets the watchdog. This simple fix
simply resets the watchdog when performing an MSC read or write.

epicardium/modules/usb.c

@@ -24,6 +24,9 @@
 #include "mx25lba.h"
 #include "msc.h"
 
+#include "mxc_sys.h"
+#include "wdt.h"
+
 /* memory access callbacks for the mass storage (FLASH) device */
 static int mscmem_init();
 static uint32_t mscmem_size(void);
@@ -96,6 +99,9 @@ static uint32_t mscmem_size(void)
 
 static int mscmem_read(uint32_t lba, uint8_t *buffer)
 {
+	/* Reset the watchdog as this interrupt might be
+	 * firing back to back for a few seconds. */
+	WDT_ResetTimer(MXC_WDT0);
 	return mx25_read(lba, buffer);
 }
 
@@ -105,6 +111,9 @@ static int mscmem_write(uint32_t lba, uint8_t *buffer)
 		//bootloader_dirty();
 	}
 	dirty = 2;
+	/* Reset the watchdog as this interrupt might be
+	 * firing back to back for a few seconds. */
+	WDT_ResetTimer(MXC_WDT0);
 	return mx25_write(lba, buffer);
 }