Core: Context structure refine

- Change the architecture context name to 'struct tfm_arch_ctx_t'.
- Rename EXC_RETURN value in LR to Macro 'EXC_RETURN_THREAD_S_PSP'.

Change-Id: Ia13f3ae5c477e4ad4dc092f11bdba1f2b32dd00b
Signed-off-by: Summer Qin <summer.qin@arm.com>
diff --git a/secure_fw/spm/spm_api.h b/secure_fw/spm/spm_api.h
index a99033a..56a112a 100644
--- a/secure_fw/spm/spm_api.h
+++ b/secure_fw/spm/spm_api.h
@@ -669,13 +669,13 @@
  * PendSV specified function.
  *
  * Parameters :
- *  ctxb        -    State context storage pointer
+ *  p_actx        -    Architecture context storage pointer
  *
  * Notes:
  *  This is a staging API. Scheduler should be called in SPM finally and
  *  this function will be obsoleted later.
  */
-void tfm_pendsv_do_schedule(struct tfm_state_context_ext *ctxb);
+void tfm_pendsv_do_schedule(struct tfm_arch_ctx_t *p_actx);
 
 /**
  * \brief                      SPM initialization implementation