configs/grinn_chiliboard_defconfig: bump to u-boot 2020.10

Fixes:
 /usr/bin/ld: scripts/dtc/dtc-parser.tab.o:(.bss+0x10): multiple definition of `yylloc';
	scripts/dtc/dtc-lexer.lex.o:(.bss+0x0): first defined here

Signed-off-by: Bartosz Bilas <b.bilas@grinn-global.com>
Reviewed-by: Marcin Niestroj <m.niestroj@grinn-global.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>