The eSDHC does not work properly if the SION bit is not set for the
bidirectional CMD signal, whatever the eSDHC instance and the selected
pad. Therefore, setting SION is mandatory for all eSDHC CMD ports. Do
this for MX25_PAD_*__ESDHCn_CMD in imx25-pinfunc.h in order to enforce
this behavior for all boards.

This had already been done for eSDHC1, but not for eSDHC2. Also, define
MX25_PAD_FEC_MDC__ESDHC2_CMD so that all the possible cases are covered
from now on.
Signed-off-by: Benoît Thébaudeau <benoit.thebaudeau.dev@gmail.com>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>