leds: leds-qpnp: Reset WLED enable register in wled init function

Reset WLED enable register in wled initialization function to avoid
unnecessary power consumption during the device boots up.

CRs-Fixed: 546571
Change-Id: Id8d8ed9d3c20e2209847457c711b7645d5de45b3
Signed-off-by: Sarada Prasanna Garnayak <c_sgarna@codeaurora.org>