The new API no longer uses the extra cd parameter that was used to store
the card presence state. Instead, this information is returned via the
function's return value. board_mmc_getcd() returns -1 to indicate that
no card-detection mechanism is implemented; 0 indicates that no card is
present and 1 is returned if it was detected that a card is present.

The rationale for this change can be found in the following email
thread:

	http://lists.denx.de/pipermail/u-boot/2011-November/110180.html



In summary, the old API was not consistent with the rest of the MMC API
which always passes a struct mmc as the first parameter. Furthermore the
cd parameter was used to mean "card absence" in some implementations and
"card presence" in others.

Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
Tested-by: Jason Liu <jason.hui@linaro.org>