driver: eth_mcux: realtime optimizations

mcux enet driver updates:
a) add mutex to access the ptp timer variables
b) use thread for rx(cooperative) andfor tx cleanup(cooperative)
c) use a thread for ptp inner clock updater(pre-empty)

This patch fixes the following issue:

```
ENET_SendFrame error: 4004
```

Signed-off-by: Hake Huang <hake.huang@oss.nxp.com>
Co-authored-by: Seb Laveze <sebastien.laveze@nxp.com>
Signed-off-by: Xabier Marquiegui <xmarquiegui@ainguraiiot.com>

drivers/ethernet/Kconfig.mcux

@@ -58,7 +58,7 @@ config ETH_MCUX_RX_BUFFERS
 config ETH_MCUX_TX_BUFFERS
 	int "Number of MCUX TX buffers"
 	default 1
-	range 1 1
+	range 1 16
 	help
 	  Set the number of TX buffers provided to the MCUX driver.