arch/x86/boot/tables.c: Remove unused variable assignment to `rom_table_end`

Change-Id: I098d1238cda16060c3566f242443007cdaf9bd82
Signed-off-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-on: http://review.coreboot.org/5106
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

src/arch/x86/boot/tables.c

@@ -212,8 +212,7 @@ void write_tables(void)
 				new_high_table_pointer - high_table_pointer);
 	} else {
 		/* The coreboot table must be in 0-4K or 960K-1M */
-		rom_table_end = write_coreboot_table(
-				     low_table_start, low_table_end,
+		write_coreboot_table(low_table_start, low_table_end,
 				     rom_table_start, rom_table_end);
 	}