usb: qmp: phy: Update SIGDET_LVL value for 8996 v2 and v3/v4 variants

Different signal detect threshold value is required to use with USB QMP
PHY for 8996 v2 and 8996 v3/v4 platforms. Hence set QSERDES_RX_SIGDET_LVL
register value as 0x18 using default table, and move 0x1B value with
misc_config to use as override for 8996 v2.

CRs-Fixed: 910111
Change-Id: Ic3e7118f9040972a8097e563b4945d6ee7b990d3
Signed-off-by: Mayank Rana <mrana@codeaurora.org>