net: ethernet: mac89x0: add missing MODULE_DESCRIPTION() macro

With ARCH=m68k, make allmodconfig && make W=1 C=1 reports:
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/net/ethernet/cirrus/mac89x0.o

Add the missing invocation of the MODULE_DESCRIPTION() macro.
Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20240618-md-m68k-drivers-net-ethernet-cirrus-v1-1-07f5bd0b64cb@quicinc.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/cirrus/mac89x0.c

@@ -554,6 +554,7 @@ static int set_mac_address(struct net_device *dev, void *addr)
 	return 0;
 }
 
+MODULE_DESCRIPTION("Macintosh CS89x0-based Ethernet driver");
 MODULE_LICENSE("GPL");
 
 static void mac89x0_device_remove(struct platform_device *pdev)