Merge branch 'devlink-errors-fmsg'

Przemek Kitszel says:

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devlink: retain error in struct devlink_fmsg

Extend devlink fmsg to retain error (patch 1),
so drivers could omit error checks after devlink_fmsg_*() (patches 2-10),
and finally enforce future uses to follow this practice by change to
return void (patch 11)

Note that it was compile tested only.

bloat-o-meter for whole series:
add/remove: 8/18 grow/shrink: 23/40 up/down: 2017/-5833 (-3816)
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Signed-off-by: David S. Miller <davem@davemloft.net>