lib: el3_runtime: Fix SPE system registers in el2_sysregs_context
lib: el3_runtime: Fix SPE system registers in el2_sysregs_context

Include EL2 registers related to SPE in EL2 context save/restore
routines if architecture supports it and platform wants to use these
features in Secure world.

Change-Id: Ie01a2c38fa5f6c907276eddec120fdfb222561a6
Signed-off-by: Arunachalam Ganapathy <dce9338f710b9095e42fdce770812a0fef195629@arm.com>

achingupta/arm-trusted-firmware,achingupta/arm-trusted-firmware