buildroot

kbd: fix install to target

The package makefile attempted to append to KBD_INSTALL_TARGET_OPTS, but this
fails when done before evaluating $(autotools-package). This is because
autotools-package uses ?= to set default values. Instead of appending we now
override KBD_INSTALL_TARGET_OPTS.

Signed-off-by: Niels Skou Olsen <niels@tonebarker.dk>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>