PCI: cpqphp: Use <linux/io.h> instead of <asm/io.h>

Use the preferred generic header file linux/io.h that already includes the
corresponding asm/io.h file.

Link: https://lore.kernel.org/r/20211013003145.1107148-2-kw@linux.com
Signed-off-by: Krzysztof Wilczyński <kw@linux.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Jonathan Derrick <jonathan.derrick@linux.dev>

drivers/pci/hotplug/cpqphp.h

@@ -15,7 +15,7 @@
 #define _CPQPHP_H
 
 #include <linux/interrupt.h>
-#include <asm/io.h>		/* for read? and write? functions */
+#include <linux/io.h>		/* for read? and write? functions */
 #include <linux/delay.h>	/* for delays */
 #include <linux/mutex.h>
 #include <linux/sched/signal.h>	/* for signal_pending() */