kbuild: uapi: simplify libc dependency logic

kbuild: uapi: simplify libc dependency logic

The only left user of the condition inverts it.

Invert the condition completely and simplify its user.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nicolas Schier <nsc@kernel.org>
Tested-by: Nicolas Schier <nsc@kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patch.msgid.link/20260227-kbuild-uapi-libc-v1-8-c17de0d19776@weissschuh.net
Signed-off-by: Nicolas Schier <nsc@kernel.org>