Fixed kernel_check

Right now, the script failed with an "expr: syntax error" and exited the if echoing that no new version is available.
The OLD_VERSION was read incorrectly, and expr compared versions from the site with " *X.YZ*-JB-CM-AOKP-SGII-PWR-CORE (root@dorimanx-virtual-machine) (gcc version 4.7.3 20130328 (prerelease) (Linaro GCC 4.7-2013.04) ) #1 SMP PREEMPT Sat May 25 17:55:03 IDT 2013"

I modified that line to compare only X.YZ with X.YZ from the site.
I tested this with 9.23.