ata: pata_mpc52xx: Prepare cleanup of powerpc's asm/prom.h

powerpc's asm/prom.h brings some headers that it doesn't
need itself.

In order to clean it up, first add missing headers in
users of asm/prom.h

Signed-off-by: Christophe Leroy <[e-mail]>
Reviewed-by: Sergey Shtylyov <[e-mail]>
Signed-off-by: Damien Le Moal <[e-mail]>

drivers/ata/pata_mpc52xx.c

···
 #include <linux/gfp.h>
 #include <linux/delay.h>
 #include <linux/libata.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
 #include <linux/of_platform.h>
 #include <linux/types.h>
 
 #include <asm/cacheflush.h>
-#include <asm/prom.h>
 #include <asm/mpc52xx.h>
 
 #include <linux/fsl/bestcomm/bestcomm.h>