leds: leds-qpnp-flash: disable headroom sense when module is disabled

Disabling headroom sense after module disable, for reducing
leakage current.

CRs-Fixed: 829939
Change-Id: Id72243eb1ff422402b01f8faba6110d8dd0637dc
Signed-off-by: Jigarkumar Kishorkumar Zala <j_zala@codeaurora.org>