tty: serial: 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
Reviewed-by: NJiri Slaby <jirislaby@kernel.org>
Signed-off-by: NChristophe Leroy <christophe.leroy@csgroup.eu>
Link: https://lore.kernel.org/r/49fc0d4b6446da630b1e9f29c4bab38f8ed087bf.1648833419.git.christophe.leroy@csgroup.euSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/cpm_uart/cpm_uart_cpm2.c

@@ -25,7 +25,6 @@
 #include <asm/io.h>
 #include <asm/irq.h>
 #include <asm/fs_pd.h>
-#include <asm/prom.h>
 
 #include <linux/serial_core.h>
 #include <linux/kernel.h>

drivers/tty/serial/mpc52xx_uart.c

@@ -38,6 +38,8 @@
 #include <linux/delay.h>
 #include <linux/io.h>
 #include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
 #include <linux/of_platform.h>
 #include <linux/clk.h>
 

drivers/tty/serial/pmac_zilog.c

@@ -51,7 +51,6 @@
 #include <asm/irq.h>
 
 #ifdef CONFIG_PPC_PMAC
-#include <asm/prom.h>
 #include <asm/machdep.h>
 #include <asm/pmac_feature.h>
 #include <asm/dbdma.h>