musb: sunxi: Use base address from device tree

Now that the musb sunxi glue driver is completely device model / device
tree driven, we should use the base address from the device tree,
instead of hard-coding it in the source code.

Fixes: 3a61b080 ("musb: sunxi: switch to the device model")
Signed-off-by: Chen-Yu Tsai <wens@csie.org>