powerpc: pseries/dtl.c should include asm/firmware.h

A randconfig build on powerpc failed with:

dtl.c: In function 'dtl_init':
dtl.c:238: error: implicit declaration of function 'firmware_has_feature'
dtl.c:238: error: 'FW_FEATURE_SPLPAR' undeclared (first use in this function)

- We need firmware.h for these definitions.
Signed-off-by: NSachin Sant <sachinp@in.ibm.com>
Signed-off-by: NJeremy Kerr <jk@ozlabs.org>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

arch/powerpc/platforms/pseries/dtl.c

@@ -25,6 +25,7 @@
 #include <asm/smp.h>
 #include <asm/system.h>
 #include <asm/uaccess.h>
+#include <asm/firmware.h>
 
 #include "plpar_wrappers.h"