ag71xx: ag71xx: use device name for debugfs entry

The ag71xx debugfs code uses the network device name
for the device specific debugfs directory. Since r38689
'ar71xx: ag71xx: fix a race involving netdev registration'
the debugfs initialization happens before the ethernet
device gets registered and the network device name contains
'eth%d' at this point. If the board setup code registers
multiple ag71xx devices, the debugfs code tries to create
the device specific dir with the same name which causes
an error like this:

  eth0: Atheros AG71xx at 0xba000000, irq 5, mode:GMII
  ag71xx ag71xx.0: connected to PHY at ag71xx-mdio.1:04 [uid=004dd041, driver=Generic PHY]
  ag71xx: probe of ag71xx.0 failed with error -12

Use the device name for the debugfs directory to avoid the
collisions. Also add an error message and change the return
code if the debugfs_create_dir call fails.

Reported-by: Ronald Wahl <ronald.wahl@raritan.com>
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@39115 3c298f89-4303-0410-b956-a3cf2f4a3e73
ar71xx: ag71xx: use mdio bus name in ar7240_probe messages

The ar7240_probe function uses the network device name
in the kernel log messages, however the name is not yet
initialized when the ar7240_probe function is called.
Use the mdio bus name in the messages to avoid ugly
log lines like the following one:

  eth%d: Found an AR7240/AR9330 built-in switch

Reported-by: Ronald Wahl <ronald.wahl@raritan.com>
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@39116 3c298f89-4303-0410-b956-a3cf2f4a3e73
ar71xx: ag71xx: store maximum frame length in the ag71xx struct

This will allow to use different values for the
different SoCs.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@39117 3c298f89-4303-0410-b956-a3cf2f4a3e73