msm: qpnp-haptic: Manage the state of PON regulator

Control the PON regulator (required to force MBG_ON) based on
the current state of haptic and maintain the regulator state
to avoid frequent enable/disable.

CRs-Fixed: 1111145
Change-Id: Ic7238a7828d1694192e890433d4247b25b5b15e1
Signed-off-by: Anirudh Ghayal <aghayal@codeaurora.org>