tpm2d: Check SWTPM environment variable for swtpm support.
* tpm2d/intel-tss.h (TSS_Create): Check SWTPM.
Cherry-picked from master commit of:
1da40db03eba4aa056f7cdf8ef90292272a4147d
- Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>