x86/eisa: Add missing include

The seperation of the EISA init missed to include linux/io.h which breaks
the build with some special configurations.

Reported-by: Ingo Molnar <[e-mail]>
Fixes: f7eaf6e00fd5 ("x86/boot: Move EISA setup to a separate file")
Signed-off-by: Thomas Gleixner <[e-mail]>

arch/x86/kernel/eisa.c

···
  */
 #include <linux/ioport.h>
 #include <linux/eisa.h>
+#include <linux/io.h>
 
 static __init int eisa_bus_probe(void)
 {