mISDN: use kstrdup() in dsp_pipeline_build
mISDN: use kstrdup() in dsp_pipeline_build

Use kstrdup instead of strlen-kmalloc-strcpy. Remove unneeded NULL
test, it will be tested inside kstrdup. Remove 0 length string test,
it has been tested in the caller of dsp_pipeline_build.

Signed-off-by: Geliang Tang <d12999005f6151b9468b6f2bd6d86bf9f7b59e02@163.com>
Signed-off-by: David S. Miller <fe08d3c717adf2ae63592e4c9aec6e3e404d8e3e@davemloft.net>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs