SPM: S-EL0 partitions support build for TC0

Add support for building Ivy for the TC0 platform. To do this
extend the Ivy build system to support building for multiple
platforms.

Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
Change-Id: I47298f00ba91f498826dd3ddd690309df01cc13e
diff --git a/spm/common/sp_debug.h b/spm/common/sp_debug.h
index 8b0bec7..e35c602 100644
--- a/spm/common/sp_debug.h
+++ b/spm/common/sp_debug.h
@@ -7,6 +7,7 @@
 enum stdout_route {
 	PL011_AS_STDOUT = 0,
 	HVC_CALL_AS_STDOUT,
+	SVC_CALL_AS_STDOUT,
 };
 
 void set_putc_impl(enum stdout_route);