samples: drivers: display: add stm32f469_disco conf file

Add stm32f749i_disco conf file to support samples display driver
applications . Increase the amount of HEAP to ensure
k_malloc allocation goes well.

Signed-off-by: Philippe Peurichard <p.peurichard@gmail.com>
diff --git a/samples/drivers/display/boards/stm32f469i_disco.conf b/samples/drivers/display/boards/stm32f469i_disco.conf
new file mode 100644
index 0000000..69c6db3
--- /dev/null
+++ b/samples/drivers/display/boards/stm32f469i_disco.conf
@@ -0,0 +1,4 @@
+# Copyright (c) 2025 STMicroelectronics
+# SPDX-License-Identifier: Apache-2.0
+
+CONFIG_HEAP_MEM_POOL_SIZE=131072