mmc: fsl_esdhc: Fix hang after 'save' command

Since commit 48e0b2bd (powerpc/esdhc: Correct judgement for DATA PIO mode)
we see mx6 systems to hang after doing a 'save' command.

Revert this commit since the original 'ifdef' logic from 7b43db92
(drivers/mmc/fsl_esdhc.c: fix compiler warnings) was the correct one.

Reported-by: Tapani Utriainen <tapani@technexion.com>
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Andy Fleming <afleming@freescale.com>