If we're built with MBEDTLS_SHAxxx_USE_A64_CRYPTO_IF_PRESENT but don't have a
way to detect the crypto extensions required, the code turns off _IF_PRESENT
and falls back to C only (with a warning). This was done after the attributes
are pushed, and the pop is done only #if defined(xxx_IF_PRESENT), so this
commit fixes that.
Signed-off-by: Tom Cosgrove <tom.cosgrove@arm.com>
