fix(el3-spmc): fix dangling pointer in FFA_CONSOLE_LOG

Fixes a dangling pointer bug in `spmc_ffa_console_log`.
`chars` was assigned to an array which went out of scope at the end of
the `if`/`else` block.

The solution is to `memcmpy` from the temporary array into `chars`,
which is now an array.

Signed-off-by: Karl Meakin <karl.meakin@arm.com>
Change-Id: I67d19ea25d09b72f38fcc67dab4acf449aa8f1b1
1 file changed