scripts/update-linux-headers: add linux/mman.h

Add linux/mman.h,asm/mman.h,asm/mman-common.h to linux-headers,
So we can use more mmap2 flags.

Signed-off-by: Zhang Yi <yi.z.zhang@linux.intel.com>
Message-Id: <f65c78d74859f815aa9c4f97407eb33361a6672c.1549555521.git.yi.z.zhang@linux.intel.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>