net: stmmac: ptp: fix potentially overflowing expression

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2122226



commit eccffcf4
Author: Xiaoliang Yang <xiaoliang.yang_1@nxp.com>
Date: Thu, 23 Dec 2021 15:39:28 +0800

    Convert the u32 variable to type u64 in a context where expression of
    type u64 is required to avoid potential overflow.

    Fixes: e9e37200 ("net: stmmac: ptp: update tas basetime after ptp adjust")
Signed-off-by: Xiaoliang Yang <xiaoliang.yang_1@nxp.com>
    Link: https://lore.kernel.org/r/20211223073928.37371-1-xiaoliang.yang_1@nxp.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Signed-off-by: Mark Salter <msalter@redhat.com>