drivers/arm/scmi: allow use of multiple SCMI channels

On systems that have multiple platform components that can interpret the
SCMI messages, there is a need to support multiple SCMI channels (one
each to those platform components). Extend the existing SCMI interface
that currently supports only a single SCMI channel to support multiple
SCMI channels.

Change-Id: Ice4062475b903aef3b5e5bc37df364c9778a62c5
Signed-off-by: Aditya Angadi <aditya.angadi@arm.com>
diff --git a/plat/arm/board/juno/include/platform_def.h b/plat/arm/board/juno/include/platform_def.h
index 998e0e3..eddd7e5 100644
--- a/plat/arm/board/juno/include/platform_def.h
+++ b/plat/arm/board/juno/include/platform_def.h
@@ -300,4 +300,7 @@
 #define PLAT_VIRT_ADDR_SPACE_SIZE	(1ULL << 32)
 #endif
 
+/* Number of SCMI channels on the platform */
+#define PLAT_ARM_SCMI_CHANNEL_COUNT	U(1)
+
 #endif /* PLATFORM_DEF_H */