mmc: rtsx: fix card poweroff bug

If the host driver removed while card in the slot, the host will not
power off card power correctly. This bug is produced because host
eject flag set before the last mmc_set_ios callback, we should set the
eject flag after power off.

Signed-off-by: Micky Ching <micky_ching@realsil.com.cn>
Signed-off-by: Chris Ball <chris@printf.net>