[rp2040] Explicit cast value of hw_set_alias

Some compilers don't support the GNU extension `typeof` so their definitions
of `hw_set_alias` can't inherit their type from their argument, and the best
we can do is have `hw_set_alias` act the same as `hw_set_alias_untyped`.
This requires an explicit cast when the macro is used instead, otherwise
IAR generates error Pe132 'expression must have pointer-to-struct-or-union
type but it has type "void *"'.

The same goes for `hw_clear_alias`.

src/portable/raspberrypi/rp2040/dcd_rp2040.c

@@ -46,8 +46,8 @@
 /* Low level controller
  *------------------------------------------------------------------*/
 
-#define usb_hw_set hw_set_alias(usb_hw)
-#define usb_hw_clear hw_clear_alias(usb_hw)
+#define usb_hw_set ((usb_hw_t *)hw_set_alias(usb_hw))
+#define usb_hw_clear ((usb_hw_t *)hw_clear_alias(usb_hw))
 
 // Init these in dcd_init
 static uint8_t *next_buffer_ptr;