Add support to indicate size and end of assembly functions

In order for the symbol table in the ELF file to contain the size of
functions written in assembly, it is necessary to report it to the
assembler using the .size directive.

To fulfil the above requirements, this patch introduces an 'endfunc'
macro which contains the .endfunc and .size directives. It also adds
a .func directive to the 'func' assembler macro.

The .func/.endfunc have been used so the assembler can fail if
endfunc is omitted.

Fixes ARM-Software/tf-issues#295

Change-Id: If8cb331b03d7f38fe7e3694d4de26f1075b278fc
Signed-off-by: Kévin Petit <kevin.petit@arm.com>
diff --git a/lib/cpus/aarch64/aem_generic.S b/lib/cpus/aarch64/aem_generic.S
index 58a64a6..ee53058 100644
--- a/lib/cpus/aarch64/aem_generic.S
+++ b/lib/cpus/aarch64/aem_generic.S
@@ -49,6 +49,7 @@
 	 * ---------------------------------------------
 	 */
 	b	dcsw_op_louis
+endfunc aem_generic_core_pwr_dwn
 
 
 func aem_generic_cluster_pwr_dwn
@@ -67,6 +68,7 @@
 	 */
 	mov	x0, #DCCISW
 	b	dcsw_op_all
+endfunc aem_generic_cluster_pwr_dwn
 
 	/* ---------------------------------------------
 	 * This function provides cpu specific
@@ -80,6 +82,7 @@
 func aem_generic_cpu_reg_dump
 	mov	x6, #0 /* no registers to report */
 	ret
+endfunc aem_generic_cpu_reg_dump
 
 
 /* cpu_ops for Base AEM FVP */