tisdk-image.bbclass: update with ARMv8 support
tisdk-image.bbclass: update with ARMv8 support

Don't hardcode toolchain path that is specific to ARMv7.
Kernel binary image is called Image.

Signed-off-by: Denys Dmytriyenko <d29de71aea38aad3a87d486929cb0aad173ae612@ti.com>

rcn-ee/meta-arago,rcn-ee/meta-arago,rcn-ee/meta-arago,rcn-ee/meta-arago,rcn-ee/meta-arago