ARM: shmobile: alt: Correct ether pfc

22b16071 ("ARM: shmobile: alt: Add pfc pins to DT") introduced pfc pins
to the alt device tree but did not reference them. This patch fixes ether
pfc by:

* Referencing ether pins
* Adding and referencing phy1 pins
* Removing ether b pins. These are not used in the configuration
  of the alt board used for testing and empirically their presence
  prevents ethernet from functioning correctly in that environment.

Reported-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>