cxl/acpi: Verify CHBS length for CXL2.0

Per CXL Spec r3.1 Table 9-21, both CXL1.1 and CXL2.0 have defined their
own length, verify it to avoid an invalid CHBS.

Additionally, this patch also removes the redundant macro CXL_RCRB_SIZE,
favoring the use of `ACPI_CEDT_CHBS_LENGTH_CXL11`, which offers clearer
semantic meaning.

[DJ: Code edited for readability suggested by djbw]

Reviewed-by: Gregory Price <gourry@gourry.net>
Signed-off-by: Li Zhijian <lizhijian@fujitsu.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Link: https://patch.msgid.link/20250410010545.99590-1-lizhijian@fujitsu.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>

Author: zhijianli88

drivers/cxl/acpi.c

@@ -11,8 +11,6 @@
 #include "cxlpci.h"
 #include "cxl.h"
 
-#define CXL_RCRB_SIZE	SZ_8K
-
 struct cxl_cxims_data {
 	int nr_maps;
 	u64 xormaps[] __counted_by(nr_maps);
@@ -479,7 +477,11 @@ static int cxl_get_chbs_iter(union acpi_subtable_headers *header, void *arg,
 	chbs = (struct acpi_cedt_chbs *) header;
 
 	if (chbs->cxl_version == ACPI_CEDT_CHBS_VERSION_CXL11 &&
-	    chbs->length != CXL_RCRB_SIZE)
+	    chbs->length != ACPI_CEDT_CHBS_LENGTH_CXL11)
+		return 0;
+
+	if (chbs->cxl_version == ACPI_CEDT_CHBS_VERSION_CXL20 &&
+	    chbs->length != ACPI_CEDT_CHBS_LENGTH_CXL20)
 		return 0;
 
 	if (!chbs->base)