xen: events: Remove redundant clear of l2i at end of round-robin loop

Signed-off-by: Keir Fraser <keir.fraser@citrix.com>
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
[ijc: forward ported from linux-2.6.18-xen.hg 991:9ba6d9f3fbc0]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>