lib: test_bitmap: clearly separate ERANGE from EINVAL tests.

This block of tests was meant to find/flag incorrect use of the ":"
and "/" separators (syntax errors) and invalid (zero) group len.

However they were specified with an 8 bit width and 32 bit operations,
so they really contained two errors (EINVAL and ERANGE).

Promote them to 32 bit so it is clear what they are meant to target.
Then we can add tests specific for ERANGE (no syntax errors, just
doing 32bit op on 8 bit width, plus a typical 9-on-8 fencepost error).

Cc: Yury Norov <yury.norov@gmail.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Yury Norov <yury.norov@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>