um/asm: Rename rep_nop() to native_pause()

Rename rep_nop() function to what it really does.

No functional change intended.

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: David Laight <david.laight.linux@gmail.com>
Link: https://patch.msgid.link/20250418083436.133148-1-ubizjak@gmail.com


Signed-off-by: Johannes Berg <johannes.berg@intel.com>