buildroot

configs/galileo: update kernel version to fix build with gcc 6.x

The kernel used so far for the galileo boards would not successfully
build with GCC versions greater than 5.

See: https://github.com/mdr78/Linux-x1000/pull/2

Signed-off-by: Nicholas Sielicki <sielicki@yandex.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>