x86/resctrl: Use _ASM_BX to avoid ifdeffery

Use the _ASM_BX macro which expands to either %rbx or %ebx, depending on
the 32-bit or 64-bit config selected.
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Reinette Chatre <reinette.chatre@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190606200044.5730-1-ubizjak@gmail.com

arch/x86/kernel/cpu/resctrl/pseudo_lock.c

@@ -431,11 +431,7 @@ static int pseudo_lock_fn(void *_rdtgrp)
 #else
 	register unsigned int line_size asm("esi");
 	register unsigned int size asm("edi");
-#ifdef CONFIG_X86_64
-	register void *mem_r asm("rbx");
-#else
-	register void *mem_r asm("ebx");
-#endif /* CONFIG_X86_64 */
+	register void *mem_r asm(_ASM_BX);
 #endif /* CONFIG_KASAN */
 
 	/*