crypto: stm32 - CRC use relaxed function

In case of arm soc support, readl and writel will
be optimized using relaxed functions

Signed-off-by: Lionel Debieve <lionel.debieve@st.com>
Reviewed-by: Fabien Dessenne <fabien.dessenne@st.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>