hammerhead: Define kernel image name to build a proper dtb binary

Change-Id: I7470078f56c666b612a625ef100a0d7b7a4200c6
hammerhead: Suppress secure erase

Use the hack to speed up flashing (by the factor of 10).

Change-Id: I921bba5561bcca23fd94c9ada4d1e433389fb6e9
hammerhead: Use interactive governor in recovery

Replace perfomance by interactive cpu governor which allows for frequency
scaling. Presently we are only using one compression thread, as this may
change in the future, use it for all available cpus.

Change-Id: I8008144d8ef74b30af9a270fbb1d4b1f0353fc7e
make it custom