mdadm: upgrade to version 4.0

mdadm: upgrade to version 4.0

3.4 -> 4.0

Removed the following upstreamed or backported patches:

 a) 0001-Fix-some-type-comparison-problems.patch
 b) 0001-Fix-typo-in-comparision.patch
 c) 0001-mdadm.h-bswap-is-already-defined-in-uclibc.patch
 d) 0001-raid6check-Fix-if-else-indentation.patch
 e) 0001-util.c-include-poll.h-instead-of-sys-poll.h.patch
 f) mdadm-3.2.2_fix_for_x32.patch

Signed-off-by: Maxin B. John <maxin.john@intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>