net: gianfar: Use __be64 * to store pointers to big endian values

net: gianfar: Use __be64 * to store pointers to big endian values

Timestamp values are read using pointers to 64-bit big endian values.
But the type of these pointers is u64 *, host byte order.
Use __be64 * instead.

Flagged by Sparse:

.../gianfar.c:2212:60: warning: cast to restricted __be64
.../gianfar.c:2475:53: warning: cast to restricted __be64

Introduced by
commit cc772ab7cdca ("gianfar: Add hardware RX timestamping support").

Compile tested only.
No functional change intended.

Signed-off-by: Simon Horman <horms@kernel.org>
Reviewed-by: Claudiu Manoil <claudiu.manoil@nxp.com>
Link: https://patch.msgid.link/20241011-gianfar-be64-v1-1-a77ebe972176@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>