Replace dynamic memory allocation in memory management with static memory allocation.
Since the static memory allocation can guarantee the allocation never failed, so
split_large_page and construct_pgentry don't need to return a errno any more.
Besides, the destroy_ept don't need to free page any more. Instead, it would memset
the eptp to 0 to make sure we can't walk this paging table again.
Tracked-On: #861
Signed-off-by: Li, Fei1 <fei1.li@intel.com>