fix(ti): fix typo in boot authentication message name

Fix AUTH_BOOT message identifier (s/IMIAGE/IMAGE).

Reported-by: Jorge Ramirez-Ortiz <jorge@foundries.io>
Signed-off-by: Andrew Davis <afd@ti.com>
Change-Id: I19eb1798c6b9dd8c3f59e05c59318c9c3be971a0