minor reformatting in ada-lang.c::ada_to_fixed_value

minor reformatting in ada-lang.c::ada_to_fixed_value

The arguments in the call to ada_to_fixed_value_create where
improperly aligned. But I also noticed that all the arguments
do fit on a single-line (up to 79 characters). So this patch
just fixes the code by putting everything on that same line.

gdb/ChangeLog:

        * ada-lang.c (ada_to_fixed_value): Minor reformatting in
        call to ada_to_fixed_value_create.