tools/testing/cxl: Remove unused SZ_512G macro

SZ_512G macro has become useless since commit b2f3b74e
("tools/testing/cxl: Move cxl_test resources to the top of memory")
so remove it directly.
Signed-off-by: Xiao Yang <yangx.jy@fujitsu.com>
Link: https://lore.kernel.org/r/20230719163103.3392-1-yangx.jy@fujitsu.comReviewed-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>

tools/testing/cxl/test/cxl.c

@@ -999,10 +999,6 @@ static void mock_companion(struct acpi_device *adev, struct device *dev)
 #define SZ_64G (SZ_32G * 2)
 #endif
 
-#ifndef SZ_512G
-#define SZ_512G (SZ_64G * 8)
-#endif
-
 static __init int cxl_rch_init(void)
 {
 	int rc, i;