Add volatile qualifier (#1283)

Add volatile qualifier

This is needed to ensure that the memory mapped address it always read.

Signed-off-by: Gaurav Aggarwal <aggarg@amazon.com>

.gitignore

@@ -11,6 +11,7 @@
 [Oo]bj/
 [Ll]og/
 [Ll]ogs/
+[Bb]uild/
 
 # CodeWarrior temporary files
 *.tdt

FreeRTOS/Demo/RISC-V-Qemu-virt_GCC/ns16550.c

@@ -20,7 +20,7 @@
  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  *
  * https://www.FreeRTOS.org
- * https://www.github.com/FreeRTOS
+ * https://github.com/FreeRTOS
  *
  */
 
@@ -54,12 +54,12 @@
 
 static uint8_t readb( uintptr_t addr )
 {
-	return *( (uint8_t *) addr );
+	return *( (volatile uint8_t *) addr );
 }
 
 static void writeb( uint8_t b, uintptr_t addr )
 {
-	*( (uint8_t *) addr ) = b;
+	*( (volatile uint8_t *) addr ) = b;
 }
 
 void vOutNS16550( struct device *dev, unsigned char c )