fix build error: "no case matching constant switch condition"

[yuguo68]

hitting the following error when building on AMD gpu

Stderr:
bitsandbytes/0.47.0._git_c0dcdf2/csrc/kernels.hip:637:18: error: no case matching constant switch condition '6' [-Werror]
  637 |           switch(OPTIMIZER)
      |                  ^~~~~~~~~
bitsandbytes/0.47.0._git_c0dcdf2/csrc/kernels.hip:2947:1: note: in instantiation of function template specialization 'kPreconditionOptimizer32bit2State<float, 6, 4096, 8>' requested here
 2947 | MAKE_PreconditionOptimizer32bit2State(ADEMAMIX, float)
      | ^
bitsandbytes/0.47.0._git_c0dcdf2/csrc/kernels.hip:2939:26: note: expanded from macro 'MAKE_PreconditionOptimizer32bit2State'
 2939 | template __global__ void kPreconditionOptimizer32bit2State<gtype, oname, 4096, 8>(gtype* g, gtype* p,  \
      |                          ^
bitsandbytes/0.47.0._git_c0dcdf2/csrc/kernels.hip:637:18: error: no case matching constant switch condition '6' [-Werror]

[matthewdouglas]

Makes sense with -Werror. LGTM, thanks!

[github-actions]

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[yuguo68]

Makes sense with -Werror. LGTM, thanks!

thank you for the quick review and removing the whitespaces!