[ARM] clean up a load of old declarations

... some of which are now in linux/*.h headers.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index f972fc3..61a2242 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -61,8 +61,7 @@
 
 extern void paging_init(struct meminfo *, struct machine_desc *desc);
 extern void reboot_setup(char *str);
-extern int root_mountflags;
-extern void _stext, _text, _etext, __data_start, _edata, _end;
+extern void _text, _etext, __data_start, _edata, _end;
 
 unsigned int processor_id;
 EXPORT_SYMBOL(processor_id);