tion of function 'msleep'

Caused by commit 6caa3b0bbdb474647f6bdd8a958ffc46f78d8d58 ("md: Remove
unnecessary #includes, #defines, and function declarations").  I added
the following patch.

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NeilBrown <neilb@suse.de>
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