Both the pointer array and the pointed data have to be const when using
__initconst to be correct.  This also fixes LTO builds that otherwise
fail with section mismatch errors.
Fixes: ec60d95b4fac ("ARM: shmobile: Basic r8a7793 SoC support")
Signed-off-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
 #include "common.h"
 #include "rcar-gen2.h"
 
-static const char *r8a7793_boards_compat_dt[] __initconst = {
+static const char * const r8a7793_boards_compat_dt[] __initconst = {
        "renesas,r8a7793",
        NULL,
 };