!466 LoongArch: fix compile error when using make allmodconfig

Merge Pull Request from: @Hongchen_Zhang 
 
1. when compile for arm platform using make allmodconfig,compile error occurred at drivers/gpu/drm/loongson/lsdc_i2c.o.
So we add the required io.h to make it fine.
2. fix drivers/vfio/pci/vfio_pci_rdwr.c compile error on LoongArch by change the 
  definition of iounmap. 
 
Link:https://gitee.com/openeuler/kernel/pulls/466 

Reviewed-by: Jialin Zhang <zhangjialin11@huawei.com> 
Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com> 

arch/loongarch/include/asm/io.h

@@ -41,7 +41,7 @@ static inline void __iomem *ioremap_prot(phys_addr_t offset, unsigned long size,
 #define ioremap(offset, size)		\
 	ioremap_prot((offset), (size), pgprot_val(PAGE_KERNEL_SUC))
 
-#define iounmap(addr) 			do { } while (0)
+#define iounmap(addr)	((void)(addr))
 
 #endif
 

drivers/gpu/drm/loongson/lsdc_i2c.c

@@ -9,6 +9,7 @@
  */
 
 #include <linux/i2c.h>
+#include <linux/io.h>
 
 #include <drm/drm_print.h>
 #include <drm/drm_device.h>