atomisp: remove sh_css_malloc indirections where we can

Where we know the buffer size is reasonably constrained we can just use kmalloc,
and where it will be large vmalloc. This still leaves a pile in the middle.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>