tpm2_createak: don't clobber created context files
tpm2_createak: don't clobber created context files

Instead use files_uniquify_filename() to find a non-existing variant of the
filename to use.

Signed-off-by: Joshua Lock <9750fc34162235efa862f2505c1a01f735e97af7@intel.com>

martinezjavier/tpm2-tools,01org/tpm2.0-tools,martinezjavier/tpm2-tools,01org/tpm2.0-tools,01org/tpm2.0-tools,martinezjavier/tpm2-tools,martinezjavier/tpm2-tools