request_suspend: change check for suspend-is-disabled.

request_suspend: change check for suspend-is-disabled.

Both request_suspend and lsusd try to abort the request if suspend is
disabled.  However as they use the same mechanism they can trip over
each other and produce the wrong result.

So leave the primary checking to lsusd.  It will remove  the 'request'
file if needed, so request_suspend will notice.  It can then check
if a suspend actually happened by examining the 'watching' file.

Also: change request_suspend to exit(2) on strange error, and exit(1)
only if suspend was blocked.

Signed-off-by: NeilBrown <neilb@suse.de>