leds: qti-flash: Fix error logging in qti_flash_led_symmetry_config()

If symmetry is enabled and user sets the brightness on switch
device directly without setting brightness on flash or torch
devices, then an error log is printed. Fix it.

Change-Id: I10cc9e3143173fb4ea9dad0ed078fde3594b6e54
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>