cxl: Isolate a few bare-metal-specific calls

A few functions are mostly common between bare-metal and guest and
just need minor tuning. To avoid crowding the backend API, introduce a
few 'if' based on the CPU being in HV mode.

Co-authored-by: Christophe Lombard <clombard@linux.vnet.ibm.com>
Signed-off-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: Christophe Lombard <clombard@linux.vnet.ibm.com>
Reviewed-by: Manoj Kumar <manoj@linux.vnet.ibm.com>
Acked-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

drivers/misc/cxl/debugfs.c

@@ -118,6 +118,10 @@ void cxl_debugfs_afu_remove(struct cxl_afu *afu)
 int __init cxl_debugfs_init(void)
 {
 	struct dentry *ent;
+
+	if (!cpu_has_feature(CPU_FTR_HVMODE))
+		return 0;
+
 	ent = debugfs_create_dir("cxl", NULL);
 	if (IS_ERR(ent))
 		return PTR_ERR(ent);