staging: csr: remove CsrMemAllocDma()

It's just a call to kmalloc(, GFP_KERNEL | GFP_DMA);

But, all memory allocated by kmalloc can be DMAed, and that's not what
GFP_DMA means, so remove that flag, and just call kmalloc(, GFP_KERNEL);

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>