kconf_check: tweak CONFIG_ regex

kconf_check: tweak CONFIG_ regex

As reported in https://bugzilla.yoctoproject.org/show_bug.cgi?id=12563,
the regex that matches valid CONFIG_ options was missing some of the
ones in net/netfilter/ipvs/Kconfig, and hence triggering invalid
option warnings.

By dropping the trailing space on the regex, we'll cover all the cases
for valid option.

(From OE-Core rev: 461a2f54751ca18e17f897b10d6c3c47dab1733a)

Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>