nitro_enclaves: Sanity check physical memory regions during merging

Sanity check the physical memory regions during the merge of contiguous
regions. Thus we can test the physical memory regions setup logic
individually, including the error cases coming from the sanity checks.

Reviewed-by: Andra Paraschiv <andraprs@amazon.com>
Signed-off-by: Longpeng <longpeng2@huawei.com>
Link: https://lore.kernel.org/r/20211107140918.2106-3-longpeng2@huawei.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>