app: aboot: enable the assert on tamper flag
app: aboot: enable the assert on tamper flag

this flag do not allow bootup of unauthorised kernel image.

CRs-Fixed: 701303
Change-Id: I8b1190a98eff49bd802531c8e8668d909626b6c1

lg-devs/g2-bootloader,t2m-foxfone/android_kernel_lk,lg-devs/g2-bootloader,mozilla-b2g/fairphone2_kernel_lk,mozilla-b2g/fairphone2_kernel_lk,t2m-foxfone/android_kernel_lk,lg-devs/g2-bootloader,mozilla-b2g/fairphone2_kernel_lk,lg-devs/g2-bootloader,t2m-foxfone/android_kernel_lk,lg-devs/g2-bootloader,mozilla-b2g/fairphone2_kernel_lk,mozilla-b2g/fairphone2_kernel_lk,t2m-foxfone/android_kernel_lk,t2m-foxfone/android_kernel_lk