network-manager: sync kernel headers comment with actual dependency

network-manager: sync kernel headers comment with actual dependency

In commit 52282828f06dc8aa3f721727f68a5096b9ed8b49
("package/network-manager: add patches to build with kernel headers
3.2"), network-manager was changed to build with kernel headers as old
as 3.2, instead of 3.7 before. The dependency was changed accordingly,
but the Config.in comment was not.

This commit fixes this inconsistency.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Acked-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>