tfm_spe_mailbox: Use local vars for local_copy_vects

Minor tidy-up to use local in_vec and out_vec in local_copy_vects.

Signed-off-by: Nicola Mazzucato <nicola.mazzucato@arm.com>
Suggested-by: Chris Brand <chris.brand@cypress.com>
Change-Id: I7179d668e42b27a1d18ccf727008cc47e549a7ef
(cherry picked from commit 64b6ea548bca14131e78bf9499ceecd3f7506206)
1 file changed