sd: sdhci: Remove block count enable check in single block transfers

In SDHCI protocol, the 'Block count enable' bit of the Transfer
Mode register is relevant only in multi block transfers. We need
not check it in single block transfers.

Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Message-id: 20170214185225.7994-5-ppandit@redhat.com
Reviewed-by: Alistair Francis <alistair.francis@xilinx.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
