arm: K3: Fix header comment match AM6 specific file function

This file used to be the common location for K3 init when AM6 was the
only device, but common code was moved to common.c and this file became
AM6 specific, correct this header text.

Signed-off-by: Andrew F. Davis <afd@ti.com>
Reviewed-by: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>