selftests/sgx: Test faulty enclave behavior

Removing a page from an initialized enclave involves three steps:
first the user requests changing the page type to SGX_PAGE_TYPE_TRIM
via an ioctl(), on success the ENCLU[EACCEPT] instruction needs to be
run from within the enclave to accept the page removal, finally the
user requests page removal to be completed via an ioctl(). Only after
acceptance (ENCLU[EACCEPT]) from within the enclave can the kernel
remove the page from a running enclave.

Test the behavior when the user's request to change the page type
succeeds, but the ENCLU[EACCEPT] instruction is not run before the
ioctl() requesting page removal is run. This should not be permitted.

Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Jarkko Sakkinen <jarkko@kernel.org>
Link: https://lkml.kernel.org/r/fa5da30ebac108b7517194c3038b52995602b996.1652137848.git.reinette.chatre@intel.com