s390/vx: add 64 and 128 bit members to __vector128 struct

Add 64 and 128 bit members to __vector128 struct in order to allow reading
of the complete value, or the higher or lower part of vector register
contents instead of having to use casts.

Add an explicit __aligned(4) statement to avoid that the alignment of the
structure changes from 4 to 8. This should make sure that no breakage
happens because of this change.

Reviewed-by: Alexander Gordeev <[e-mail]>
Signed-off-by: Heiko Carstens <[e-mail]>

arch/s390/include/uapi/asm/types.h

···
 typedef __signed__ long saddr_t;
 
 typedef struct {
-	__u32 u[4];
-} __vector128;
+	union {
+		struct {
+			__u64 high;
+			__u64 low;
+		};
+		__uint128_t v;
+		__u32 u[4];
+	};
+} __attribute__((packed, aligned(4))) __vector128;
 
 #endif /* __ASSEMBLY__ */