phy: meson8b-usb2: fix offsets for some of the registers

The register offsets for REG_DBG_UART (and all following) were off by
0x4. This was not a problem yet because these registers are currently
not used by the driver.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Reviewed-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>