uclibc: remove version from the uclibc-ng config option

uclibc: remove version from the uclibc-ng config option

For the moment, we probably don't want to have several versions of
uClibc-ng supported at the same time. In preparation to the bump of
uClibc-ng to 1.0.1, this commit gets rid of the version number from
the uclibc-ng config option so that we don't have to rename this
option over and over again each time a new uClibc-ng release is
made. This would be annoying in terms of Config.in.legacy handling.

Since the option BR2_UCLIBC_NG_VERSION_1_0_0 has never been part of
any Buildroot release, we don't have to add anything to
Config.in.legacy.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>