linux/io.h defines readq() and ioremap_nocache() / iounmap() functions.

If not included, the build fails:

intel_telemetry_pltdrv.c:1165:31: warning: assignment makes pointer from integer without a cast [-Wint-conversion]
intel_telemetry_pltdrv.c:1165:33: error: implicit declaration of function 'ioremap_nocache' [-Werror=implicit-function-declaration]
intel_telemetry_pltdrv.c:1202:3: error: implicit declaration of function 'iounmap' [-Werror=implicit-function-declaration]
intel_telemetry_pltdrv.c:900:20: error: implicit declaration of function 'readq' [-Werror=implicit-function-declaration]

Fix this by including linux/io.h.
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>