mdadm: Introduce pr_info()

mdadm: Introduce pr_info()

Feedback was given to avoid informational pr_err() calls that print
to stderr, even though that's done all through out the code.

Using printf() directly doesn't maintain the same format (an "mdadm"
prefix on every line.

So introduce pr_info() which prints to stdout with the same format
and use it for a couple informational pr_err() calls in Create().

Future work can make this call used in more cases.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Acked-by: Kinga Tanska <kinga.tanska@linux.intel.com>
Reviewed-by: Xiao Ni <xni@redhat.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Acked-by: Coly Li <colyli@suse.de>
Acked-by: Paul Menzel <pmenzel@molgen.mpg.de>
Signed-off-by: Jes Sorensen <jes@trained-monkey.org>