staging: mt7621-pci: Include preferred headers

This fixes the following checkpatch warnings:
Use #include <linux/pci.h> instead of <asm/pci.h>
Use #include <linux/io.h> instead of <asm/io.h>
Signed-off-by: Oliver Hübers <oliver.huebers@web.de>
Signed-off-by: Vanessa Borgmann <nessa.x@web.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/mt7621-pci/pci-mt7621.c

@@ -44,8 +44,8 @@
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/version.h>
-#include <asm/pci.h>
-#include <asm/io.h>
+#include <linux/pci.h>
+#include <linux/io.h>
 #include <asm/mips-cm.h>
 #include <linux/init.h>
 #include <linux/module.h>