drm/amdkfd: Fix error code sign for EINVAL in svm_ioctl()

Use negative error code -EINVAL instead of positive EINVAL in the default
case of svm_ioctl() to conform to Linux kernel error code conventions.

Fixes: 42de677f79 ("drm/amdkfd: register svm range")
Signed-off-by: Qianfeng Rong <rongqianfeng@vivo.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdkfd/kfd_svm.c

@@ -4261,7 +4261,7 @@ svm_ioctl(struct kfd_process *p, enum kfd_ioctl_svm_op op, uint64_t start,
 		r = svm_range_get_attr(p, mm, start, size, nattrs, attrs);
 		break;
 	default:
-		r = EINVAL;
+		r = -EINVAL;
 		break;
 	}