When the code to use the PTP HW clock was added, it didn't update
the Kconfig entry for the PTP dependency, leading to build errors,
so update the Kconfig entry to depend on PTP_1588_CLOCK_OPTIONAL.

aarch64-linux-ld: drivers/net/wireless/intel/iwlwifi/mvm/ptp.o: in function `iwl_mvm_ptp_init':
drivers/net/wireless/intel/iwlwifi/mvm/ptp.c:294: undefined reference to `ptp_clock_register'
drivers/net/wireless/intel/iwlwifi/mvm/ptp.c:294:(.text+0xce8): relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol `ptp_clock_register'
aarch64-linux-ld: drivers/net/wireless/intel/iwlwifi/mvm/ptp.c:301: undefined reference to `ptp_clock_index'
drivers/net/wireless/intel/iwlwifi/mvm/ptp.c:301:(.text+0xd18): relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol `ptp_clock_index'
aarch64-linux-ld: drivers/net/wireless/intel/iwlwifi/mvm/ptp.o: in function `iwl_mvm_ptp_remove':
drivers/net/wireless/intel/iwlwifi/mvm/ptp.c:315: undefined reference to `ptp_clock_index'
drivers/net/wireless/intel/iwlwifi/mvm/ptp.c:315:(.text+0xe80): relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol `ptp_clock_index'
aarch64-linux-ld: drivers/net/wireless/intel/iwlwifi/mvm/ptp.c:319: undefined reference to `ptp_clock_unregister'
drivers/net/wireless/intel/iwlwifi/mvm/ptp.c:319:(.text+0xeac): relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol `ptp_clock_unregister'

Fixes: 1595ecce ("wifi: iwlwifi: mvm: add support for PTP HW clock (PHC)")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/all/202308110447.4QSJHmFH-lkp@intel.com/
Cc: Krishnanand Prabhu <krishnanand.prabhu@intel.com>
Cc: Luca Coelho <luciano.coelho@intel.com>
Cc: Gregory Greenman <gregory.greenman@intel.com>
Cc: Johannes Berg <johannes.berg@intel.com>
Cc: Kalle Valo <kvalo@kernel.org>
Cc: linux-wireless@vger.kernel.org
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: netdev@vger.kernel.org
Reviewed-by: Simon Horman <horms@kernel.org>
Tested-by: Simon Horman <horms@kernel.org> # build-tested
Acked-by: Richard Cochran <richardcochran@gmail.com>
Acked-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230812052947.22913-1-rdunlap@infradead.orgSigned-off-by: Johannes Berg <johannes.berg@intel.com>