Fixup MBED_PATCH_VERSION

MBED_PATCH_VERSION should have been updated to 3 for this release.

Author: adbridge

mbed.h

@@ -22,7 +22,7 @@
 // RTOS present, this is valid only for mbed OS 5
 #define MBED_MAJOR_VERSION 5
 #define MBED_MINOR_VERSION 2
-#define MBED_PATCH_VERSION 1
+#define MBED_PATCH_VERSION 3
 
 #else
 // mbed 2