dmaengine: kill some dubious WARN_ONCEs
dmaengine: kill some dubious WARN_ONCEs

dma_find_channel and dma_issue_pending_all are good places to warn about
improper api usage.  However, warning correctly means synchronizing with
dma_list_mutex, i.e. too much overhead for these fast-path calls.

Reported-by: Ingo Molnar <9dbbbf0688fedc85ad4da37637f1a64b8c718ee2@elte.hu>
Signed-off-by: Dan Williams <24ee2bf0bd8ac766c348bf1f0639943bac1535c6@intel.com>

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