selftests/sgx: Dump enclave memory map

Often, it's useful to check whether /proc/self/maps looks sane when
dealing with memory mapped objects, especially when they are JIT'ish
dynamically constructed objects. Therefore, dump "/dev/sgx_enclave"
matching lines from the memory map in FIXTURE_SETUP().

Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>