bl32: add secure interrupt handling in AArch32 sp_min

Add support for a minimal secure interrupt service in sp_min for
the AArch32 implementation. Hard code that only FIQs are handled.

Introduce bolean build directive SP_MIN_WITH_SECURE_FIQ to enable
FIQ handling from SP_MIN.

Configure SCR[FIQ] and SCR[FW] from generic code for both cold and
warm boots to handle FIQ in secure state from monitor.

Since SP_MIN architecture, FIQ are always trapped when system executes
in non secure state. Hence discard relay of the secure/non-secure
state in the FIQ handler.

Change-Id: I1f7d1dc7b21f6f90011b7f3fcd921e455592f5e7
Signed-off-by: Etienne Carriere <etienne.carriere@st.com>
diff --git a/include/bl32/sp_min/platform_sp_min.h b/include/bl32/sp_min/platform_sp_min.h
index 70c5c14..6c7e0cc 100644
--- a/include/bl32/sp_min/platform_sp_min.h
+++ b/include/bl32/sp_min/platform_sp_min.h
@@ -17,4 +17,7 @@
 void sp_min_plat_arch_setup(void);
 entry_point_info_t *sp_min_plat_get_bl33_ep_info(void);
 
+/* Platforms that enable SP_MIN_WITH_SECURE_FIQ shall implement this api */
+void sp_min_plat_fiq_handler(uint32_t id);
+
 #endif /* __PLATFORM_SP_MIN_H__ */