mmc: sdhci: move initialisation of command error member

When a command is started, logically it has no error.  Initialise the
command's error member to zero whenever we start a command.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
[ Goes with "mmc: sdhci: fix command response CRC error handling" ]
Cc: stable@vger.kernel.org # v4.5+
Tested-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>