The commit 154fb14d ("x86/hyperv: Replace kmap() with
kmap_local_page()") keeps the BUG_ON() to check if kmap_local_page()
fails.

But in fact, kmap_local_page() always returns a valid kernel address
and won't return NULL here. It will BUG on its own if it fails. [1]

So directly use memcpy_to_page() which creates local mapping to copy.

[1]: https://lore.kernel.org/lkml/YztFEyUA48et0yTt@iweiny-mobl/Suggested-by: NFabio M. De Francesco <fmdefrancesco@gmail.com>
Suggested-by: NIra Weiny <ira.weiny@intel.com>
Reviewed-by: NIra Weiny <ira.weiny@intel.com>
Signed-off-by: NZhao Liu <zhao1.liu@intel.com>
Link: https://lore.kernel.org/r/20221020083820.2341088-1-zhao1.liu@linux.intel.comSigned-off-by: NWei Liu <wei.liu@kernel.org>