parisc: move head.S to head.text section

And explicitly list it in vmlinux.lds...

Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>

arch/parisc/kernel/head.S

@@ -32,7 +32,8 @@ ENTRY(boot_args)
 	.word 0 /* arg3 */
 END(boot_args)
 
-	.section .text.head
+	__HEAD
+
 	.align	4
 	.import init_thread_union,data
 	.import fault_vector_20,code    /* IVA parisc 2.0 32 bit */