[POWERPC] Remove cmd_line from head*.S

It is just a C char array, so declare it thusly.

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/kernel/setup-common.c b/arch/powerpc/kernel/setup-common.c
index 50ef38c..36c90ba 100644
--- a/arch/powerpc/kernel/setup-common.c
+++ b/arch/powerpc/kernel/setup-common.c
@@ -76,6 +76,8 @@
 
 unsigned long klimit = (unsigned long) _end;
 
+char cmd_line[COMMAND_LINE_SIZE];
+
 /*
  * This still seems to be needed... -- paulus
  */