package/dtc: bump version to 1.6.0

package/dtc: bump version to 1.6.0

When host compiler is gcc 10 (for example on Fedora 32), dtc 1.5.1
fail to build with the error:
/usr/bin/ld: dtc-parser.tab.o:(.bss+0x20): multiple definition of `yylloc'; dtc-lexer.lex.o:(.bss+0x0): first defined here
collect2: error: ld returned 1 exit status

dtc 1.6.0 fixes this issue in the commit:
https://git.kernel.org/pub/scm/utils/dtc/dtc.git/commit/?id=0e9225eb0dfec51def612b928d2f1836b092bc7e

Also adopt new spacing convention in .hash files (two spaces).

Signed-off-by: Julien Olivain <juju@cotds.org>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>