Fix build errors by #including <linux/io.h>.

../drivers/platform/x86/intel_punit_ipc.c: In function 'ipc_read_status':
../drivers/platform/x86/intel_punit_ipc.c:55:2: error: implicit declaration of function 'readl' [-Werror=implicit-function-declaration]
  return readl(ipcdev->base[type][BASE_IFACE]);
../drivers/platform/x86/intel_punit_ipc.c: In function 'ipc_write_cmd':
../drivers/platform/x86/intel_punit_ipc.c:60:2: error: implicit declaration of function 'writel' [-Werror=implicit-function-declaration]
  writel(cmd, ipcdev->base[type][BASE_IFACE]);

Fixes: 447ae316 ("x86: Don't include linux/irq.h from asm/hardirq.h")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Zha Qipeng <qipeng.zha@intel.com>
Cc: platform-driver-x86@vger.kernel.org
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>