drivers/xen-tpmfront: Fix compile issue with missing option.
drivers/xen-tpmfront: Fix compile issue with missing option.

Randy reports:

x86_64:

drivers/built-in.o: In function `xen_tpmfront_init':
xen-tpmfront.c:(.init.text+0x257c): undefined reference to `xenbus_register_frontend'

This is nicely fixed by selecting the XenBus frontend module.

Reported-by: Randy Dunlap <6f29df8e90a57f1ba61ffd63b0468c86bb6d3a99@infradead.org>
Signed-off-by: Konrad Rzeszutek Wilk <da3a51b335cef0eb0e2c329c5ef6bcd6acef687a@oracle.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs