aboot: Check if booting into FFBM
aboot: Check if booting into FFBM

FFBM is needed to start the system in native Android to shorten boot time
in case of factory testing. FFBM mode representation is string of the type
"ffbm-xx" where xx is number that denotes the FFBM submode.
LK reads that string from the misc partition during boot and passes it
transparently to kernel bootargs

Change-Id: Ib1a73463bb776b02478b626d174b93a9f592a0d8

M1cha/android_bootable_bootloader_lk,mozilla-b2g/kernel_lk,Redmi-dev/android_bootable_lk,mozilla-b2g/kernel_lk,Redmi-dev/android_bootable_lk,t2m-foxfone/kernel_lk,M1cha/lktris,Foxda-Tech/polaris-bootable-bootloader-lk,efidroid/lk,lg-devs/g2-bootloader,lg-devs/g2-bootloader,t2m-foxfone/kernel_lk,mozilla-b2g/kernel_lk,t2m-foxfone/kernel_lk,Redmi-dev/android_bootable_lk,jbott/lk_gee,CanarySolutions/little-kernel,Foxda-Tech/argo8-bootable-bootloader-lk,mozilla-b2g/kernel_lk,detule/lk-g2-spr,lg-devs/g2-bootloader,chirayudesai/android_bootable_bootloader_lk,Foxda-Tech/argo8-bootable-bootloader-lk,t2m-foxfone/android_kernel_lk,jbott/lk_gee,detule/lk-g2-spr,jsr-d10/android_bootable_bootloader_lk,lg-devs/g2-bootloader,efidroid/lk,Foxda-Tech/polaris-bootable-bootloader-lk,M1cha/lktris,chirayudesai/android_bootable_bootloader_lk,idor/dk50-bootable_bootloader_lk,t2m-foxfone/android_kernel_lk,chirayudesai/android_bootable_bootloader_lk,jsr-d10/android_bootable_bootloader_lk,Foxda-Tech/argo8-bootable-bootloader-lk,mozilla-b2g/fairphone2_kernel_lk,jsr-d10/android_bootable_bootloader_lk,M1cha/android_bootable_bootloader_lk,jbott/lk_gee,t2m-foxfone/android_kernel_lk,Foxda-Tech/argo8-bootable-bootloader-lk,CanarySolutions/little-kernel,t2m-foxfone/kernel_lk,jsr-d10/android_bootable_bootloader_lk,M1cha/lktris,M1cha/android_bootable_bootloader_lk,Foxda-Tech/polaris-bootable-bootloader-lk,mozilla-b2g/kernel_lk,Redmi-dev/android_bootable_lk,idor/dk50-bootable_bootloader_lk,M1cha/lktris,mozilla-b2g/fairphone2_kernel_lk,detule/lk-g2-spr,jbott/lk_gee,CanarySolutions/little-kernel,CanarySolutions/little-kernel,chirayudesai/android_bootable_bootloader_lk,CanarySolutions/little-kernel,efidroid/lk,efidroid/lk,Redmi-dev/android_bootable_lk,idor/dk50-bootable_bootloader_lk,idor/dk50-bootable_bootloader_lk,t2m-foxfone/kernel_lk,detule/lk-g2-spr,M1cha/lktris,M1cha/android_bootable_bootloader_lk,detule/lk-g2-spr,efidroid/lk,chirayudesai/android_bootable_bootloader_lk,mozilla-b2g/fairphone2_kernel_lk,jsr-d10/android_bootable_bootloader_lk,M1cha/android_bootable_bootloader_lk,Foxda-Tech/argo8-bootable-bootloader-lk,mozilla-b2g/fairphone2_kernel_lk,jbott/lk_gee,mozilla-b2g/fairphone2_kernel_lk,idor/dk50-bootable_bootloader_lk,Foxda-Tech/polaris-bootable-bootloader-lk,t2m-foxfone/android_kernel_lk,lg-devs/g2-bootloader,M1cha/android_bootable_bootloader_lk,t2m-foxfone/android_kernel_lk,Foxda-Tech/polaris-bootable-bootloader-lk