dmaengine: use DEFINE_IDR for static initialization
dmaengine: use DEFINE_IDR for static initialization

We could use DEFINE_IDR for statically allocated idr
that allow us to save a few lines of code.

And also remove unneeded mutex_init() for dma_list_mutex, as
dma_list_mutex is initialized automatically by DEFINE_MUTEX().

Signed-off-by: Axel Lin <b6ffd6973e972cb999e8e535ab74da7fee0c035f@gmail.com>
Signed-off-by: Dan Williams <24ee2bf0bd8ac766c348bf1f0639943bac1535c6@intel.com>

TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs