This used to be the case, but no longer is; Apple stopped using the TPM in Intel macs shortly after they launched[1] and have not brought it back since.

DSMOS.kext has another function, however; it is involved in Apple's binary protection scheme[2] for certain OSX binaries. Essentially, OSX ships with certain important binaries (such as loginwindow, SystemUIServer, Finder, and Dock) that have certain vm pages encrypted. Decrypting these pages for use requires DSMOS.kext.

[1]: http://osxbook.com/book/bonus/chapter10/tpm/ [2]: http://www.osxbook.com/book/bonus/chapter7/binaryprotection/