vmlinux.lds.h: Remove a reference to no longer used sections .text..refcount

Sections .text..refcount were previously used to hold an error path code
for fast refcount overflow protection on x86, see commit 7a46ec0e
("locking/refcounts, x86/asm: Implement fast refcount overflow
protection") and commit 564c9cc8 ("locking/refcounts, x86/asm: Use
unique .text section for refcount exceptions").

The code was replaced and removed in commit fb041bb7


("locking/refcount: Consolidate implementations of refcount_t") and no
sections .text..refcount are present since then.

Remove then a relic referencing these sections from TEXT_TEXT to avoid
confusing people, like me. This is a non-functional change.

Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
Link: https://lore.kernel.org/r/20230711125054.9000-1-petr.pavlu@suse.com
Signed-off-by: Kees Cook <keescook@chromium.org>