This patch adds new ports-implemented mask, which is required to get
achi working on the mainline. Without this patch value read from
PORTS_IMPL register which is zero would not enable any ports for
software to use.

Fixes: 566d1827 ("libata: disable forced PORTS_IMPL for >= AHCI 1.3")
Cc: stable@vger.kernel.org # v4.5+
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Reviewed-by: Andy Gross <andy.gross@linaro.org>
Signed-off-by: Tejun Heo <tj@kernel.org>