net/designware - switch driver to phylib usage

With this change driver will benefit from existing phylib and thus
custom phy functionality implemented in the driver will go away:
 * Instantiation of the driver is now much shorter - 2 parameters
instead of 4.
 * Simplified phy management/functoinality in driver is replaced with
rich functionality of phylib.
 * Support of custom phy initialization is now done with existing
"board_phy_config".

Note that after this change some previously used config options
(driver-specific PHY configuration) will be obsolete and they are simply
substituted with similar options of phylib.

For example:
 * CONFIG_DW_AUTONEG - no need in this one. Autonegotiation is enabled
by default.
 * CONFIG_DW_SEARCH_PHY - if one wants to specify attached phy
explicitly CONFIG_PHY_ADDR board config option has to be used, otherwise
automatically the first discovered on MDIO bus phy will be used

I believe there's no need now in "doc/README.designware_eth" because
user only needs to instantiate the driver with "designware_initialize"
whose prototype exists in "include/netdev.h".

Cc: Joe Hershberger <joe.hershberger@ni.com>
Cc: Vipin Kumar <vipin.kumar@st.com>
Cc: Stefan Roese <sr@denx.de>
Cc: Mischa Jonker <mjonker@synopsys.com>
Cc: Shiraz Hashim <shiraz.hashim@st.com>
Cc: Albert ARIBAUD <albert.u.boot@aribaud.net>
Cc: Amit Virdi <amit.virdi@st.com>
Cc: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
diff --git a/board/spear/spear310/spear310.c b/board/spear/spear310/spear310.c
index 70f9aa1..a4c6a8e 100644
--- a/board/spear/spear310/spear310.c
+++ b/board/spear/spear310/spear310.c
@@ -54,8 +54,7 @@
 
 #if defined(CONFIG_DESIGNWARE_ETH)
 	u32 interface = PHY_INTERFACE_MODE_MII;
-	if (designware_initialize(0, CONFIG_SPEAR_ETHBASE, CONFIG_DW0_PHY,
-				interface) >= 0)
+	if (designware_initialize(CONFIG_SPEAR_ETHBASE, interface) >= 0)
 		ret++;
 #endif
 #if defined(CONFIG_MACB)