Fix ref-to-mut-static warnings in more examples

Missed these in the previous commit because I did not test locally with
the `rt` feature enabled.

Author: BryanKadzban

examples/stm32f7disco-qspi-flash/main.rs

@@ -123,8 +123,8 @@ fn memory_example_dma(
 
     // Create pinned versions for DMA transfers
     let mut stream = stream;
-    let mut read_buffer = unsafe { Pin::new(&mut READ_BUFFER) };
-    let mut page_buffer = unsafe { Pin::new(&mut PAGE_BUFFER) };
+    let mut read_buffer = unsafe { Pin::new(&mut *core::ptr::addr_of_mut!(READ_BUFFER)) };
+    let mut page_buffer = unsafe { Pin::new(&mut *core::ptr::addr_of_mut!(PAGE_BUFFER)) };
 
     ///////////////////////
     // Test erase + read //

examples/stm32f7disco-screen/main.rs

@@ -103,7 +103,7 @@ fn main() -> ! {
     let mut display = screen::Stm32F7DiscoDisplay::new(perif.LTDC, perif.DMA2D);
     display
         .controller
-        .config_layer(Layer::L1, unsafe { &mut FB_LAYER1 }, PixelFormat::RGB565);
+        .config_layer(Layer::L1, unsafe { &mut *core::ptr::addr_of_mut!(FB_LAYER1) }, PixelFormat::RGB565);
 
     display.controller.enable_layer(Layer::L1);
     display.controller.reload();