drivers: net: replace UINT64_MAX with U64_MAX

U64_MAX is well defined now while the UINT64_MAX is not, so we fall
back to drivers' own definition as below:

	#ifndef UINT64_MAX
	#define UINT64_MAX             (u64)(~((u64)0))
	#endif

I believe this is in one phy driver then copied and pasted to other phy
drivers.

Replace the UINT64_MAX with U64_MAX to clean up the source code.

Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
Signed-off-by: David S. Miller <davem@davemloft.net>