context_mgmt: declare extern cm_set_next_context() for AArch32

This change avoids warning when setting -Wmissing-prototypes to
compile bl1_context_mgmt.c.

Reported-by: Yann Gautier <yann.gautier@st.com>
Signed-off-by: Etienne Carriere <etienne.carriere@st.com>

bl1/bl1_fwu.c

@@ -52,8 +52,6 @@ static unsigned int sec_exec_image_id = INVALID_IMAGE_ID;
 /* Authentication status of each image. */
 extern unsigned int auth_img_flags[];
 
-void cm_set_next_context(void *cpu_context);
-
 /*******************************************************************************
  * Top level handler for servicing FWU SMCs.
  ******************************************************************************/

include/lib/el3_runtime/context_mgmt.h

@@ -86,6 +86,7 @@ static inline void cm_set_next_context(void *context)
 
 #else
 void *cm_get_next_context(void);
+void cm_set_next_context(void *context);
 #endif /* AARCH32 */
 
 #endif /* __CM_H__ */