GIC: Add API to set interrupt priority

API documentation updated.

Change-Id: Ib700eb1b8ca65503aeed0ac4ce0e7b934df67ff9
Co-authored-by: Yousuf A <yousuf.sait@arm.com>
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>
diff --git a/include/plat/common/platform.h b/include/plat/common/platform.h
index 671aa61..03f529c 100644
--- a/include/plat/common/platform.h
+++ b/include/plat/common/platform.h
@@ -79,6 +79,7 @@
 unsigned int plat_ic_get_interrupt_active(unsigned int id);
 void plat_ic_disable_interrupt(unsigned int id);
 void plat_ic_enable_interrupt(unsigned int id);
+void plat_ic_set_interrupt_priority(unsigned int id, unsigned int priority);
 
 /*******************************************************************************
  * Optional common functions (may be overridden)