leds: qti-flash: Initialize rc in qti_flash_led_symmetry_config()

Initialize rc just for sanity so that it is not used uninitialized in
the return path.

Fixes: 568fc7ac ("leds: qti-flash: Handle all-enabled led mask separately")
Change-Id: I77caac87781b7a2ad2de0ecb13c5b3cd9ca3707b
Signed-off-by: Guru Das Srinagesh <gurus@codeaurora.org>