wolfssl: Do not activate HW acceleration on armvirt by default

wolfssl: Do not activate HW acceleration on armvirt by default

The armvirt target is also used to run OpenWrt in lxc on other targets
like a Raspberry Pi. If we set WOLFSSL_HAS_CPU_CRYPTO by default the
wolfssl binray is only working when the CPU supports the hardware crypto
extension.

Some targets like the Raspberry Pi do not support the ARM CPU crypto
extension, compile wolfssl without it by default. It is still possible
to activate it in custom builds.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>