ptp: clockmatrix: remove 5 second delay before entering write phase mode

Remove write phase mode 5 second setup delay, not needed.

Signed-off-by: Min Li <min.li.xe@renesas.com>
Link: https://lore.kernel.org/r/1607442117-13661-2-git-send-email-min.li.xe@renesas.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>