ionic: fix ptp support config breakage

When IONIC=y and PTP_1588_CLOCK=m were set in the .config file
the driver link failed with undefined references.

We add the dependancy
	depends on PTP_1588_CLOCK || !PTP_1588_CLOCK
to clear this up.

If PTP_1588_CLOCK=m, the depends limits IONIC to =m (or disabled).
If PTP_1588_CLOCK is disabled, IONIC can be any of y/m/n.

Fixes: 61db421d ("ionic: link in the new hw timestamp code")
Reported-by: kernel test robot <lkp@intel.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Allen Hubbe <allenbh@pensando.io>
Signed-off-by: Shannon Nelson <snelson@pensando.io>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: David S. Miller <davem@davemloft.net>