[FIX] vfs unable to mount root fs unknown-block

A RHEL update today fucked up a RHEL system, giving: “vfs unable to mount root fs unknown-block”. Fix:

1. Boot from RHEL CD
2. Choose rescue mode
3. Start (with network)
4. Type: chroot /mnt/sysimage (to work in the actual disk)
5. Go and remove the oldest kernel, find oldest kernel by typing `rpm -q kernel`
6. Remove by doing: `rpm -e kernel-2.6.32-358.18.1.el6.x86_64` (replace versions ;) )
Reinstall the kernel with `yum reinstall kernel`

Should fix it.

chroot /mnt/sysimage
rpm -q kernel
rpm -e kernel-2.6.32-358.18.1.el6.x86_64
yum reinstall kernel