I2O: Fix "defined but not used" build warnings

drivers/message/i2o/exec-osm.c:539: warning: `i2o_exec_lct_notify' defined but not used

comes when CONFIG_I2O_LCT_NOTIFY_ON_CHANGES=n, because its only callsite
is #ifdef'ed as such. So let's #ifdef the function definition also. Also
move the definition to before the callsite, to get rid of forward prototype.

[akpm@linux-foundation.org: fix warnings]
Signed-off-by: Satyam Sharma <satyam@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>