arch: use Kconfig variable for coreboot table size

Instead of hard coding a #define in each architecture's
tables.c for the coreboot table size in cbmem use a Kconfig
varible. This aids in aligning on a common write_tables()
implementation instead of duplicating the code for each
architecture.

Change-Id: I09c0f56133606ea62e9a9c4c6b9828bc24dcc668
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/14429
Tested-by: build bot (Jenkins)
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

src/arch/arm/tables.c

@@ -23,7 +23,7 @@
 #include <cbmem.h>
 #include <lib.h>
 
-#define MAX_COREBOOT_TABLE_SIZE (8 * 1024)
+#define MAX_COREBOOT_TABLE_SIZE CONFIG_COREBOOT_TABLE_SIZE
 
 void write_tables(void)
 {