KVM: x86 emulator: fix JMP_REL

Change JMP_REL to call to register_address_increment(): the operands size
should not effect the calculation of the eip, instead the ad_bytes should
affect it.

Signed-off-by: Izik Eidus <izike@qumranet.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>