[media] media: Sanitise the reserved fields of the G_TOPOLOGY IOCTL arguments

The argument structs are used in arrays for G_TOPOLOGY IOCTL. The
arguments themselves do not need to be aligned to a power of two, but
aligning them up to the largest basic type alignment (u64) on common ABIs
is a good thing to do.

The patch changes the size of the reserved fields to 5 or 6 u32's and
aligns the size of the struct to 8 bytes so we do no longer depend on the
compiler to perform the alignment.

While at it, add __attribute__ ((packed)) to these structs as well.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

include/uapi/linux/media.h

@@ -297,14 +297,14 @@ struct media_v2_entity {
 	__u32 id;
 	char name[64];		/* FIXME: move to a property? (RFC says so) */
 	__u32 function;		/* Main function of the entity */
-	__u16 reserved[12];
-};
+	__u32 reserved[6];
+} __attribute__ ((packed));
 
 /* Should match the specific fields at media_intf_devnode */
 struct media_v2_intf_devnode {
 	__u32 major;
 	__u32 minor;
-};
+} __attribute__ ((packed));
 
 struct media_v2_interface {
 	__u32 id;
@@ -316,22 +316,22 @@ struct media_v2_interface {
 		struct media_v2_intf_devnode devnode;
 		__u32 raw[16];
 	};
-};
+} __attribute__ ((packed));
 
 struct media_v2_pad {
 	__u32 id;
 	__u32 entity_id;
 	__u32 flags;
-	__u16 reserved[9];
-};
+	__u32 reserved[5];
+} __attribute__ ((packed));
 
 struct media_v2_link {
 	__u32 id;
 	__u32 source_id;
 	__u32 sink_id;
 	__u32 flags;
-	__u32 reserved[5];
-};
+	__u32 reserved[6];
+} __attribute__ ((packed));
 
 struct media_v2_topology {
 	__u64 topology_version;
@@ -351,7 +351,7 @@ struct media_v2_topology {
 	__u32 num_links;
 	__u32 reserved4;
 	__u64 ptr_links;
-};
+} __attribute__ ((packed));
 
 static inline void __user *media_get_uptr(__u64 arg)
 {