refactor(ethos-n): split up SMC call handling

Doing all the SMC call handling in a single function and using specific
names for the x1-4 parameters is no longer practical for upcoming
additions to the SiP service. Handling of the different SMC functions
have therefore been split into separate functions.

Signed-off-by: Mikael Olsson <mikael.olsson@arm.com>
Change-Id: If28da8df0f13c449d1fdb2bd9d792d818ec5e1af
1 file changed