u-boot-cubox-i: Fix SD offset to align with mainline value

The intended value was 69K but the sector number was wrong, fix it to
proper value as it aligns it with U-Boot mainline.

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
linux-congatec: Upgrade to cgt_imx_3.10.31_1.1.0_beta2

Update the linux-congatec for the 3.10.31_1.1.0_beta2 kernel.

Signed-off-by: Alex de Cabo <alejandro.de-cabo-garcia@congatec.com>
Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
u-boot-congatec: Change environment mmcroot variable

Since SD naming with 3.10.31 kernel changes, this patch
modifies the variable mmcroot.

Signed-off-by: Alex de Cabo <alejandro.de-cabo-garcia@congatec.com>
Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>