Fix OMV2 build.
#define OMV_DMA_MEMORY SRAM2 // Misc DMA buffers
#define OMV_FB_SIZE (151K) // FB memory: header + QVGA/GS image
-#define OMV_FB_ALLOC_SIZE (14K) // minimum fb alloc size
+#define OMV_FB_ALLOC_SIZE (12K) // minimum fb alloc size
#define OMV_STACK_SIZE (4K)
#define OMV_HEAP_SIZE (52K)
