leds: qpnp-wled: Add sync register writes in WLED driver probe

Add consecutive sync register writes in WLED driver probe.
This is needed for properly reflecting the configuration values
written for the WLED strings.

Change-Id: I252d3ee69ef3b0b67a3b137230a0b2a67f3e90d1
Signed-off-by: Shantanu Jain <shjain@codeaurora.org>