USB: msm_otg: Fix a bug in charger detection procedure

USB PHY is put into non-driving mode and pull-down resistors on DP
and DM are disabled before starting the charger detection.  The
PHY is put into driving mode at the end of the charger detection
without enabling the pull-down resistors.  Due to this DP is
pulled high when a dedicated charger is connected.  USB controller
is not allowing PHY suspend if line state is non-zero when charger
is connected.  Enable pull-down resistors at the end of charger
detection to resolve this issue.

CRs-Fixed: 509608
Change-Id: Ic1fc663b397e29e62d526b4146e92c93c84240ac
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>