x86, asm, cleanup: Replace open-coded control register values with symbolic

Clean up an unnecessary open-coded control register values.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/n/tip-um7za1nzf6brb17o0h4om6e3@git.kernel.org

arch/x86/kernel/cpu/mtrr/cyrix.c

@@ -167,7 +167,7 @@ static void post_set(void)
 	setCx86(CX86_CCR3, ccr3);
 
 	/* Enable caches */
-	write_cr0(read_cr0() & 0xbfffffff);
+	write_cr0(read_cr0() & ~X86_CR0_CD);
 
 	/* Restore value of CR4 */
 	if (cpu_has_pge)