convert license headers to SPDX

Includes license review of 3rd-party files, adding missing upstream
headers, and moving the UNSW OZPLB license into its own file rather
than replicating it in the header.

elfloader-tool: explicitly link config libs

explicitly link kernel_autoconf and elfloader_Config
since the global config lib is going to be remove

Only corrupt scratchpad register in smc_handler

r5 is a callee saved register that isn't being restored by the handler. To
simplify the handling of both the caller and handler, use the only available
scratch pad register instead.

Fix whitespace

- remove trailing whitespace
- remove duplicate blank lines
- remove blank lines at end of file

Fix licenses

elfloader: support to load the kernel in NS SVC

The elfloder for i.MX6 sabre now can be configured
to load the kernel in secure monitor, secure supervisor,
and nonsecure supervisor.