In arm64, glibc-open of /dev/xpmem is hooked in sys_openat. This
commit adds xpmem_openat which is called by sys_openat.
This commit silently applies copy_from_user fix to sys_open as well.
Change-Id: I3b4f7bf0e152c359250bb2b56910db9192390cb1
Fujitsu: POSTK_DEBUG_ARCH_DEP_46, POSTK_DEBUG_ARCH_DEP_62