leds: leds-qpnp: avoid truncation in qpnp_led_masked_write function

Since the last parameter of qpnp_led_masked_write function is
of type 'u8', make sure that only value of type 'u8' is passed
to this parameter of function to avoid truncation.

Change-Id: If047f844fc45713b77c4561a88253dade3c4c478
Signed-off-by: Abinaya P <abinayap@codeaurora.org>