SPM: Implement SPCI open/close handle SMCs

Introduce SMCs that open and close handles according to the SPCI
specification.

Change-Id: I65f365f15612e01aa445e783e96e48ae275c39fd
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
diff --git a/services/std_svc/spm/spm_private.h b/services/std_svc/spm/spm_private.h
index cfd85a3..9a4e82b 100644
--- a/services/std_svc/spm/spm_private.h
+++ b/services/std_svc/spm/spm_private.h
@@ -84,6 +84,7 @@
 /* Functions to handle Secure Partition contexts */
 void spm_cpu_set_sp_ctx(unsigned int linear_id, sp_context_t *sp_ctx);
 sp_context_t *spm_cpu_get_sp_ctx(unsigned int linear_id);
+sp_context_t *spm_sp_get_by_uuid(const uint32_t (*svc_uuid)[4]);
 
 #endif /* __ASSEMBLY__ */