tpm2_certify: allow setting of (or empty) qualifying data

[AndreasFuchsTPM]

Currently, qualifying data for the return blob is hard coded:

tpm2-tools/tools/tpm2_certify.c

Lines 79 to 82 in b4bf516

	TPM2B_DATA qualifying_data = {
	.size = 4,
	.buffer = { 0x00, 0xff, 0x55,0xaa },
	};

This should be either empty or settable by CLI parameters.

If we decide to switch to empty by default, this will be a breaking change !