scripts/esdk-tools: use a dedicated, static directory for esdk tools
This allows easier replication of esdk environment (which provides
a curated, limited set of tools that for example does not include bitbake)
in a standard yocto build. Switchover between various sets can be achieved
via PATH manipulation.
Signed-off-by: Alexander Kanavin <alex@linutronix.de> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>