ASoC: wcd9335: Avoid wrong decimator connection

Previously assigned decimator value gets wrongly used in
following iterations leading to improper decimator connection
to slimbus port. Avoid this issue by declaring the variable
locally.

Change-Id: Ifbff8da9a3e594ee065a9beab7d9f8f65a4853ea
Signed-off-by: Chaithanya Krishna Bacharaju <chaithan@codeaurora.org>