add common phy reset code into a common function.

Signed-off-by: Heiko Schocher <hs@denx.de>
Cc: Andreas Bießmann <andreas.devel@googlemail.com>
Cc: Bo Shen <voice.shen@atmel.com>
Cc: Jens Scharsig <esw@bus-elektronik.de>
Cc: Sergey Lapin <slapin@ossfans.org>
Cc: Stelian Pop <stelian@popies.net>
Cc: Albin Tonnerre <albin.tonnerre@free-electrons.com>
Cc: Eric Benard <eric@eukrea.com>
Cc: Markus Hubig <mhubig@imko.de>
Acked-by: Jens Scharsig (BuS Elektronik) <esw@bus-elektronik.de>
Tested-by: Jens Scharsig (BuS Elektronik) <esw@bus-elektronik.de>
Tested-by: Bo Shen <voice.shen@atmel.com>
Acked-by: Bo Shen <voice.shen@atmel.com>
Signed-off-by: Andreas Bießmann <andreas.devel@googlemail.com>