staging: csr: remove CsrMemAlloc()

It's just calling kmalloc(, GFP_KERNEL), so call that instead.
A few places should be calling kzalloc(), so do that, and remove the
call to memset at the same time.

Cc: Mikko Virkkilä <mikko.virkkila@bluegiga.com>
Cc: Lauri Hintsala <Lauri.Hintsala@bluegiga.com>
Cc: Riku Mettälä <riku.mettala@bluegiga.com>
Cc: Veli-Pekka Peltola <veli-pekka.peltola@bluegiga.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>