staging: ccree: remove unused and redundant variable idx

staging: ccree: remove unused and redundant variable idx

Variable idx is being set but never read and thus it can be
removed because it is redundant. Cleans up clang build warnings:

warning: Value stored to 'idx' during its initialization is never read
warning: Value stored to 'idx' is never read
warning: Value stored to 'idx' is never read

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>