parisc: asm/pdc.h should include asm/page.h

Fixes this build error:
arch/parisc/kernel/pdc_cons.c:117: error: '__PAGE_OFFSET' undeclared
Signed-off-by: Alexander Beregalov <a.beregalov@gmail.com>
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>

arch/parisc/include/asm/pdc.h

@@ -343,6 +343,8 @@
 
 #ifdef __KERNEL__
 
+#include <asm/page.h> /* for __PAGE_OFFSET */
+
 extern int pdc_type;
 
 /* Values for pdc_type */