e1000e: e1000e_cyclecounter_read(): incvalue is 32 bits, not 64

"incvalue" variable holds a result of "er32(TIMINCA) &
E1000_TIMINCA_INCVALUE_MASK" and used in "do_div(temp, incvalue)"
as a divisor.

Thus, "u64 incvalue" declaration is probably a mistake.
Even though it seems to be a harmless one, let's fix it.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/e1000e/netdev.c

@@ -4300,7 +4300,8 @@ static cycle_t e1000e_cyclecounter_read(const struct cyclecounter *cc)
 	}
 
 	if ((hw->mac.type == e1000_82574) || (hw->mac.type == e1000_82583)) {
-		u64 incvalue, time_delta, rem, temp;
+		u64 time_delta, rem, temp;
+		u32 incvalue;
 		int i;
 
 		/* errata for 82574/82583 possible bad bits read from SYSTIMH/L