ipc4: Clean up toolchain definitions

__packed and __aligned are defined in compiler_attributes.h, which
wasn't included, and when building for Zephyr that needs to include
the zephyr/toolchain.h header which is the original source of those
macros.

Transitive headers were saving this, but building for posix/fuzzing
works differently.

Signed-off-by: Andy Ross <andyross@google.com>

src/include/ipc4/notification.h

@@ -25,6 +25,7 @@
 
 #include <stdint.h>
 #include <ipc/header.h>
+#include <sof/compiler_attributes.h>
 
 /* ipc4 notification msg */
 enum sof_ipc4_notification_type {

xtos/include/sof/compiler_attributes.h

@@ -7,6 +7,8 @@
 
 #ifdef __ZEPHYR__
 
+#include <zephyr/toolchain.h>
+
 /* Get __sparse_cache and __sparse_force definitions if __CHECKER__ is defined */
 #include <zephyr/debug/sparse.h>