arm64/sve: Fix a couple of magic numbers for the Z-reg count

There are some hand-written instances of "32" to express the number
of SVE Z-registers.

Since this code was written a #define was added for this, so
convert trivial instances of this magic number as appropriate.

No functional change.
Reviewed-by: Julien Grall <julien.grall@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>

arch/arm64/kernel/fpsimd.c

@@ -412,7 +412,7 @@ static void __fpsimd_to_sve(void *sst, struct user_fpsimd_state const *fst,
 	unsigned int i;
 	__uint128_t *p;
 
-	for (i = 0; i < 32; ++i) {
+	for (i = 0; i < SVE_NUM_ZREGS; ++i) {
 		p = (__uint128_t *)ZREG(sst, vq, i);
 		*p = arm64_cpu_to_le128(fst->vregs[i]);
 	}
@@ -466,7 +466,7 @@ static void sve_to_fpsimd(struct task_struct *task)
 		return;
 
 	vq = sve_vq_from_vl(task->thread.sve_vl);
-	for (i = 0; i < 32; ++i) {
+	for (i = 0; i < SVE_NUM_ZREGS; ++i) {
 		p = (__uint128_t const *)ZREG(sst, vq, i);
 		fst->vregs[i] = arm64_le128_to_cpu(*p);
 	}