ARM: dts: STiH407-family: Add ports-implemented property in sata nodes

Despite ST AHCI version = 1.3, reading HOST_PORTS_IMPL
returns 0. So force HOST_PORTS_IMPL to 1 by using
ports-implemented DT property.

Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Reviewed-by: Peter Griffin <peter.griffin@linaro.org>