s2io: Generate complete messages using single line DBG_PRINTs

Single line log messages should be emitted by a single call
where possible.

Converted multiple calls to DBG_PRINT to single call form.
Removed "s2io:" preface from DBG_PRINTs.

The DBG_PRINT macro now emits a log level and is surrounded by
a do {...} while (0)

All s2io log output is now prefaced with KBUILD_MODNAME ": "
via pr_fmt.

The DBG_PRINT macro should probably be converted to use the
dev_<level> form eventually.

Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: Sreenivasa Honnur <sreenivasa.honnur@neterion.com>
Signed-off-by: David S. Miller <davem@davemloft.net>