uci: Fix extra semicolons warnings

Found with clang's -Wextra-semi-stmt

Fixes:

error: empty expression statement has no effect; remove unnecessary ';' to
silence this warning [-Werror,-Wextra-semi-stmt]
                UCI_TRAP_SAVE(ctx, error);
                                         ^
error: empty expression statement has no effect; remove unnecessary ';' to
silence this warning [-Werror,-Wextra-semi-stmt]
        UCI_TRAP_SAVE(ctx, ignore);

error: empty expression statement has no effect; remove unnecessary ';' to
silence this warning [-Werror,-Wextra-semi-stmt]
        };

Signed-off-by: Rosen Penev <rosenp@gmail.com>