usb: repeater: Add Qualcomm PMIC eUSB2 driver

PM8550B contains a eUSB2 repeater used for making the eUSB2 from
SM8550 USB 2.0 compliant.

Add a platform specific repeater driver. It implements ops for init,
reset and power on/off. On init, there is a configuration table that
needs to be written to the repeater's registers.

Signed-off-by: Abel Vesa <abel.vesa@linaro.org>