power: qpnp-smbcharger: force DPF_DMF between uv and src_det irq

When usb is inserted, it could take up to 600mS for charger h/w to run
APSD. APSD run involves charger changing the USB DP and DM lines for
charger type detection. Ensure that the usb driver is instructed to keep
the lines floating while this is happening. In other words ensure that
the dp_dm property is always set to DPF_DMF while we are between a falling
usbin_uv and a rising src_detect interrupt.

Note that all use cases are expected to call set_usb_psy_dp_dm() to set
DP_DM property, where the check for usbin_uv and src_detect interrupt is
done. This rule does not apply to usbin_uv interrupt handler where the
interrupt states are known and the property can be set directly.

Change-Id: Ifa2bd84312c58257e1e878e9ff51987b4a29b03e
Signed-off-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>