[FABG-793] Non-conflicting namespace for pkcs11 import

The pkcs11 namespace of the "github.com/miekg/pkcs11" import in
pkg/core/cryptosuite/common/pkcs11/contextHandle.go overlaps with the package
name pkcs11

If libltdl-dev is not installed, the upstream pkcs11 package will not compile,
and the linters confuse the upstream pkcs11 with the local package pkcs11,
causing them to fail.

Change-Id: I4224b75b47d33c1a040749597bd8c9a4fdfa4885
Signed-off-by: Nye Liu <nye@blockdaemon.com>

Author: nyetwurk