amdkfd: use <linux/mman.h> instead of <uapi/asm-generic/mman-common.h>

The latter is a default version of <asm/mman.h> and not for driver use.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>