Some boards cannot do voltage negotiation but need to set the VSELECT
bit forcely to ensure it to work at 1.8V.

This commit adds CONFIG_SYS_FSL_ESDHC_FORCE_VSELECT flag for this use.
Signed-off-by: NOtavio Salvador <otavio@ossystems.com.br>

For LS102xA, the processor is in little-endian mode, while esdhc IP is
in big-endian mode. CONFIG_SYS_FSL_ESDHC_LE and CONFIG_SYS_FSL_ESDHC_BE
are added. So accessing ESDHC registers can be determined by ESDHC IP's
endian mode.
Signed-off-by: NAlison Wang <alison.wang@freescale.com>