dmaengine: pch: fix compilation for alpha target
dmaengine: pch: fix compilation for alpha target

commit 4828b493 introduced COMPILE_TEST for this driver and this cause compile
failure on alpha as kzalloc wasnt availble for this arch in included header, so
explictly add slab.h

Reported-by: kbuild test robot <24f7fe9d205c8a9f6ade0c2894e14303ca16087f@intel.com>
Signed-off-by: Vinod Koul <5cf69c63beb17bf38d63aa0e923ee8256af0e205@intel.com>

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