zephyr: alloc: Limit heap size on MTK platforms

MTK platforms are built with CONFIG_SYS_HEAP_SMALL_ONLY. If heap
size is greater than 0x7fff chunk units, it throws an assert at boot.

Signed-off-by: Andrew Perepech <andrew.perepech@mediatek.com>

Author: andrew-mtk

zephyr/lib/alloc.c

@@ -124,7 +124,13 @@ extern char _mtk_adsp_sram_end;
 #define SRAM_SIZE  DT_REG_SIZE(DT_NODELABEL(sram0))
 #define SRAM_END   (SRAM_START + SRAM_SIZE)
 #define heapmem ((uint8_t *)ALIGN_UP((uintptr_t)&_mtk_adsp_sram_end, PLATFORM_DCACHE_ALIGN))
+
+/* Heap size is limited to 0x7fffU chunk units when CONFIG_SYS_HEAP_SMALL_ONLY is set */
+#if defined(CONFIG_SYS_HEAP_SMALL_ONLY)
+#define HEAPMEM_SIZE MIN(((uint8_t *)SRAM_END - heapmem), 0x7fff * 8)
+#else
 #define HEAPMEM_SIZE ((uint8_t *)SRAM_END - heapmem)
+#endif /* CONFIG_SYS_HEAP_SMALL_ONLY */
 
 #else