init/config: Do not select BUILD_BIN2C for IKCONFIG

Since commit 13610aa9 ("kernel/configs: use .incbin directive to
embed config_data.gz"), IKCONFIG no longer uses BUILD_BIN2C so prevent
it from being selected in Kconfig.

Reviewed-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>