cryptsetup: don't bother waiting for TPM2 devices if we are on EFI and EFI...

cryptsetup: don't bother waiting for TPM2 devices if we are on EFI and EFI says there is no TPM2 device

Note that this means EFI-systems with a manually added TPM device won't
be supported automatically, but given that the TPM2 trust model kinda
requires firmware support I doubt it matters supporting this. And in all
other cases it speeds things up a bit.