platform/x86/amd/pmc: Fix implicit declaration error on i386

Add depended header file to fix error on i386 due to implicit declaration
of function ‘writeq’.

Fixes: 2dc77993cb5e ("platform/x86/amd/pmc: Add AMD MP2 STB functionality")
Reported-by: kernel test robot <[e-mail]>
Closes: https://lore.kernel.org/oe-kbuild-all/[e-mail]/
Suggested-by: Andy Shevchenko <[e-mail]>
Signed-off-by: Basavaraj Natikar <[e-mail]>
Reviewed-by: Kuppuswamy Sathyanarayanan <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Hans de Goede <[e-mail]>

drivers/platform/x86/amd/pmc/mp2_stb.c

···
 #include <linux/debugfs.h>
 #include <linux/device.h>
 #include <linux/io.h>
+#include <linux/io-64-nonatomic-lo-hi.h>
 #include <linux/iopoll.h>
 #include <linux/pci.h>
 #include <linux/sizes.h>