driver: dw: Use base_addr variable to set dir.

Change Summary:
Update Base addr to set direction to use Aligned IP base address instead
of Port Base Address. Port Base Address + offset to direction register
will set incorrect value for Port B,C & D. For ex: In cases when more than
1 port is configured on the same IP, the DTS node for port B will start
at offset 0xC. Calculating the port using Port Base will yield offset of
PORTB DIR register which is at offset 0x10 from Aligned Base, and as a
result will result in setting DIR register of PORTC instead.

Signed-off-by: Ravik Hasija <ravikh@fb.com>