msm8226_defconfig: Enable PPPoE Configuration in Kernel

PPPoE is a customer requirement for QRD. This patch enables PPP
and PPPoE configuration in the kernel for msm8x26 devices.

CRs-Fixed: 495547
Change-Id: I9e057f72b557f138932a02af2212256d3cb476b9
Signed-off-by: Harout Hedeshian <harouth@codeaurora.org>