linux: stop if one linux patches doesn't apply

If you have several linux patches directories, Buildroot does not stop
if one patches of the first directories don't apply. This patch fixes
this.

Signed-off-by: Sébastien Szymanski <sebastien.szymanski@armadeus.com>
Acked-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>