This function is used in `fec_ptp_enable_pps()` through
struct cyclecounter read(). Forward declarations make
it clearer, what's happening.
Fixes: 61d5e2a251fb ("fec: Fix timer capture timing in `fec_ptp_enable_pps()`")
Suggested-by: Frank Li <Frank.li@xxxxxxx>
Link: https://lore.kernel.org/netdev/20240805144754.2384663-1-csokas.bence@xxxxxxxxx/T/#ma6c21ad264016c24612048b1483769eaff8cdf20
Signed-off-by: Csókás, Bence <csokas.bence@xxxxxxxxx>