tests: lib: cmsis_dsp: Fix -Wsometimes-uninitialized warning

[thughes]

Building with clang warns:

tests/lib/cmsis_dsp/distance/src/u32.c:82:3: error: variable 'val' is used uninitialized whenever switch default is taken [-Werror,-Wsometimes-uninitialized]
                default:
                ^~~~~~~
tests/lib/cmsis_dsp/distance/src/u32.c:87:19: note: uninitialized use occurs here
                output[index] = val;
                                ^~~
tests/lib/cmsis_dsp/distance/src/u32.c:47:16: note: initialize the variable 'val' to silence this warning
                float32_t val;
                             ^
                              = 0.0

Hitting the default switch will assert, so this won't cause any problems as written, but it doesn't hurt to initialize the variable.

[kartben]

It feels like there has to be a better solution since this now means there is a very good chance the compiler will generate an additional instruction, will it not?

[thughes]

It feels like there has to be a better solution since this now means there is a very good chance the compiler will generate an additional instruction, will it not?

It's a test. Does it really matter?

[kartben]

It feels like there has to be a better solution since this now means there is a very good chance the compiler will generate an additional instruction, will it not?

It's a test. Does it really matter?

Uh of course, I missed that, sorry!