Switch to Linux kernel version 4.14.40 from the TI SDK 05.00.00.15 (TI
SDK release date: 26.07.2018).
Bump u-boot version to 2018.07.
Tested on Beaglebone Black and Beaglebone White
Signed-off-by: Lothar Felten <lothar.felten@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>