arm64: fix mask in atomic_testand{set,clear}_64

These macros generate both the 32- and 64-bit ops, but the mask was hard
coded for 32-bit ops, causing the 64-bit ops always to affect only the
low 32 bits.

PR:		252324
Reported by:	gbe, mmel
Reviewed by:	markj, mmel
Tested by:	mmel, rwatson
Sponsored by:	Dell EMC Isilon
Differential Revision:	https://reviews.freebsd.org/D27886

sys/arm64/include/atomic.h

@@ -409,7 +409,7 @@ _ATOMIC_TEST_OP_PROTO(t, op, _llsc)					\
 	uint##t##_t mask, old, tmp;					\
 	int res;							\
 									\
-	mask = 1u << (val & 0x1f);					\
+	mask = ((uint##t##_t)1) << (val & (t - 1));			\
 	__asm __volatile(						\
 	    "1: ldxr		%"#w"2, [%3]\n"				\
 	    "  "#llsc_asm_op"	%"#w"0, %"#w"2, %"#w"4\n"		\
@@ -427,7 +427,7 @@ _ATOMIC_TEST_OP_PROTO(t, op, _lse)					\
 {									\
 	uint##t##_t mask, old;						\
 									\
-	mask = 1u << (val & 0x1f);					\
+	mask = ((uint##t##_t)1) << (val & (t - 1));			\
 	__asm __volatile(						\
 	    ".arch_extension lse\n"					\
 	    "ld"#lse_asm_op"	%"#w"2, %"#w"0, [%1]\n"			\