This patch adds support for a cpu context management library. This
library will be used to:
1. Share pointers to secure and non-secure state cpu contexts between
runtime services e.g. PSCI and Secure Payload Dispatcher services
2. Set SP_EL3 to a context structure which will be used for
programming an ERET into a lower EL
3. Provide wrapper functions to save and restore EL3 & EL1
state. These functions will in turn use the helper functions in
context.S
Change-Id: I655eeef83dcd2a0c6f2eb2ac23efab866ac83ca0
Achin Gupta