ARM: shmobile: r8a7793: proper constness with __initconst

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>

arch/arm/mach-shmobile/setup-r8a7793.c

@@ -19,7 +19,7 @@
 #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,
 };