[media] media/radio: fix radio-miropcm20.c build with io.h header file

Fix build errors in radio-miropcm20.c due to missing header file:

drivers/media/radio/radio-miropcm20.c: In function 'rds_waitread':
drivers/media/radio/radio-miropcm20.c:90:3: error: implicit declaration of function 'inb' [-Werror=implicit-function-declaration]
drivers/media/radio/radio-miropcm20.c: In function 'rds_rawwrite':
drivers/media/radio/radio-miropcm20.c:106:3: error: implicit declaration of function 'outb' [-Werror=implicit-function-declaration]

Reported-by: Jim Davis <jim.epost@gmail.com>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/radio/radio-miropcm20.c

@@ -27,6 +27,7 @@
 
 #include <linux/module.h>
 #include <linux/init.h>
+#include <linux/io.h>
 #include <linux/delay.h>
 #include <linux/videodev2.h>
 #include <linux/kthread.h>