sunxi: mmc: ignore card detect in SPL

sunxi: mmc: ignore card detect in SPL

The sunxi MMC code does not use the DM in the SPL, as we don't have a
device tree available that early, also no space for it.
This also means we cannot access the card-detect GPIO information from
there, so we have Kconfig symbols called CONFIG_MMCx_CD_PIN, which each
board has to define. This is a burden, also requires extra GPIO code in
the SPL.
As the SPL is the natural successor of the BootROM (from which we are
loaded), we can actually ignore the CD pin completely, as this is what
the BootROM does as well: CD GPIOs are board specific, but the BootROM
is not, so accesses the MMC devices anyway.
Also, as we must have been loaded from an MMC device when reaching this
code, there must have been a card in the slot.

Remove the card detect code from the non-DM implementation of the sunxi
MMC driver, to get rid of this unneeded code.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Samuel Holland <samuel@sholland.org>
Tested-by: Samuel Holland <samuel@sholland.org>