x86, setup: fix comment in the "glove box" code

Impact: Comment change only

The glove box is about avoiding problems with *registers* being
touched, not *memory*.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

arch/x86/boot/bioscall.S

@@ -10,7 +10,7 @@
 
 /*
  * "Glove box" for BIOS calls.  Avoids the constant problems with BIOSes
- * touching memory they shouldn't be.
+ * touching registers they shouldn't be.
  */
 
 	.code16