refactor(lib/smc): Use #define for RMI error codes

The internal enum status_t is removed and the error codes
are defined as per the RMI definition.

Signed-off-by: Yousuf A <yousuf.sait@arm.com>
Signed-off-by: Soby Mathew <soby.mathew@arm.com>
Change-Id: I93703feec65cdaf946601e09e623d7fba10f2151
2 files changed