cmd/sbi: format KVM version

Format the KVM implementation number in a human readable form.

With the patch output of the sbi command for Linux 5.19.1 looks like:

    => sbi
    SBI 0.3
    KVM 5.19.1
    Machine:
      Vendor ID 0
      Architecture ID 7005c
      Implementation ID 7005c
    Extensions:
      SBI Base Functionality
      Timer Extension
      IPI Extension
      RFENCE Extension
      Hart State Management Extension
      System Reset Extension

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>