refactor(spm-mm): reorganize secure partition manager shim code

In preparation for adding the support for SEL0 SP in EL3 SPMC,
restructure the existing SPM_MM shim code in a way that allows reuse
of the code for both SPM_MM interface and FF-A EL3 SPMC interface. The
code for changing exception levels is identical for both.

With this restructuring of the code, the shim exception code is moved to
the common sub-directory.

Signed-off-by: Sayanta Pattanayak <sayanta.pattanayak@arm.com>
Signed-off-by: Nishant Sharma <nishant.sharma@arm.com>
Change-Id: Iadda9cf73f12b56e6a1d31fc21b5ba5dc355867f
diff --git a/services/std_svc/spm/spm_mm/spm_mm_setup.c b/services/std_svc/spm/spm_mm/spm_mm_setup.c
index 04dc212..4e65c9c 100644
--- a/services/std_svc/spm/spm_mm/spm_mm_setup.c
+++ b/services/std_svc/spm/spm_mm/spm_mm_setup.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017-2022, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2017-2023, ARM Limited and Contributors. All rights reserved.
  * Copyright (c) 2021, NVIDIA Corporation. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
@@ -21,7 +21,7 @@
 
 #include "spm_common.h"
 #include "spm_mm_private.h"
-#include "spm_mm_shim_private.h"
+#include "spm_shim_private.h"
 
 /* Setup context of the Secure Partition */
 void spm_sp_setup(sp_context_t *sp_ctx)