configs/snps_arc*_defconfig: update u-boot version
With this commit we update u-boot version to 2018.05 for
Synopsys boards. U-boot version 2018.05 was released recently
and includes significant changes for ARC boards:
* Fix for compile-time warning for AXS10x
* Add support of platform-specific commands for HSDK
* Add support for on-board SPI flash on HSDK
Signed-off-by: Evgeniy Didin <didin@synopsys.com>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Cc: arc-buildroot@synopsys.com
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>