sunxi: usb_phy: Swap check for disconnect threshold

Before this commit the code for determining the disconnect threshold was
checking for sun4i or sun6i assuming that those where the exception and
that newer SoCs use a disconnect threshold of 2 like sun7i does.

But it turns out that newer SoCs actually use a disconnect threshold of 3
and sun5i and sun7i are the exceptions, so check for those instead.

Here are the settings from the various Allwinner SDK sources:
 sun4i-a10: USBC_Phy_Write(usbc_no, 0x2a, 3, 2);
 sun5i-a13: USBC_Phy_Write(usbc_no, 0x2a, 2, 2);
 sun6i-a31: USBC_Phy_Write(usbc_no, 0x2a, 3, 2);
 sun7i-a20: USBC_Phy_Write(usbc_no, 0x2a, 2, 2);
 sun8i-a23: USBC_Phy_Write(usbc_no, 0x2a, 3, 2);
 sun8i-h3:  USBC_Phy_Write(usbc_no, 0x2a, 3, 2);
 sun9i-a80: USBC_Phy_Write(usbc_no, 0x2a, 3, 2);

Note this commit makes no functional changes for sun4i - sun7i, and
changes the disconnect threshold for sun8i to match what Allwinner uses.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Ian Campbell <ijc@hellion.org.uk>