arm: socfpga: cyclone5-socdk: Probe DWC2 UDC from OF instead of hard-coded data

arm: socfpga: cyclone5-socdk: Probe DWC2 UDC from OF instead of hard-coded data

This patch adds the necessary OF alias for the UDC node, which let's
the code locate the DWC2 UDC base address in OF instead of hard-coding
it into the U-Boot binary. The code is adjusted to use the address from
OF instead of the hard-coded one. Finally, the hard-coded address is
removed and USB DM support is enabled.

Signed-off-by: Marek Vasut <[email protected]>
Cc: Chin Liang See <[email protected]>
Cc: Dinh Nguyen <[email protected]>
Cc: Lukasz Majewski <[email protected]>
Cc: Lukasz Majewski <[email protected]>