sun50i: h5: Orange Pi Zero Plus: Fix SdCard detection

The Detection pin is at PF6 and not at PH13 like defined before. I
checked the schematics and now I am am not seeing this error message any
more:
Loading Environment from FAT... Card did not respond to voltage select!

CONFIG_MMC_SUNXI_SLOT_EXTRA is also not needed because the second MCC
slot is for the Wifi card.

Fixes: 76d69eb0

 ("sun50i: h5: Add initial Orange Pi Zero Plus support")
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Reviewed-by: Jagan Teki <jagan@openedev.com>