makefile: add ffast math flags

Change-Id: Iba7ec3e427ef7e57c514a6b6b44c2343b7869ae1
makefile: add a few more linaro optimisations

Change-Id: I3e685ae189c0242c649a35eaad836749c4002268
init: kconfig: fix redefined prompt warning

Change-Id: Id8674ab5e4c836715a9ee4c7cf27b7864048bb16