prevent build error

[...]
install -m 644 Kconfig dot-config wrs_release_defconfig /home/awujek/wrs/repo/build/images/wr/etc
install: cannot stat ‘Kconfig’: No such file or directory
install: cannot stat ‘dot-config’: No such file or directory
install: cannot stat ‘wrs_release_defconfig’: No such file or directory
make[1]: *** [install] Error 1
make[1]: Leaving directory `/home/awujek/wrs/repo/wr-switch-sw/userspace/dot-config'
make: *** [install] Error 1
[...]
Signed-off-by: Adam Wujek <adam.wujek@cern.ch>