The hyperv utilities use PTP clock interfaces and should depend a
a kconfig symbol such that they will be built as a loadable module or
builtin so that linker errors do not happen.

Prevents these build errors:

ld: drivers/hv/hv_util.o: in function `hv_timesync_deinit':
hv_util.c:(.text+0x37d): undefined reference to `ptp_clock_unregister'
ld: drivers/hv/hv_util.o: in function `hv_timesync_init':
hv_util.c:(.text+0x738): undefined reference to `ptp_clock_register'

Fixes: 3716a49a ("hv_utils: implement Hyper-V PTP source")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: kernel test robot <lkp@intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Wei Liu <wei.liu@kernel.org>
Cc: Dexuan Cui <decui@microsoft.com>
Cc: linux-hyperv@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20211126023316.25184-1-rdunlap@infradead.orgSigned-off-by: Wei Liu <wei.liu@kernel.org>