net: phylink: fix sphinx complaint about invalid literal

sphinx complains about the use of "%PHYLINK_PCS_NEG_*":

Documentation/networking/kapi:144: ./include/linux/phylink.h:601: WARNING: Inline literal start-string without end-string.
Documentation/networking/kapi:144: ./include/linux/phylink.h:633: WARNING: Inline literal start-string without end-string.

These are not valid symbols so drop the '%' prefix.

Alternatively we could use %PHYLINK_PCS_NEG_\* (escape the *)
or use normal literal ``PHYLINK_PCS_NEG_*`` but there is already
a handful of un-adorned DEFINE_* in this file.

Fixes: f99d471a ("net: phylink: add PCS negotiation mode")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Link: https://lore.kernel.org/all/20230626162908.2f149f98@canb.auug.org.au/Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/phylink.h

@@ -600,7 +600,7 @@ void pcs_get_state(struct phylink_pcs *pcs,
  *
  * The %neg_mode argument should be tested via the phylink_mode_*() family of
  * functions, or for PCS that set pcs->neg_mode true, should be tested
- * against the %PHYLINK_PCS_NEG_* definitions.
+ * against the PHYLINK_PCS_NEG_* definitions.
  */
 int pcs_config(struct phylink_pcs *pcs, unsigned int neg_mode,
 	       phy_interface_t interface, const unsigned long *advertising,
@@ -630,7 +630,7 @@ void pcs_an_restart(struct phylink_pcs *pcs);
  *
  * The %mode argument should be tested via the phylink_mode_*() family of
  * functions, or for PCS that set pcs->neg_mode true, should be tested
- * against the %PHYLINK_PCS_NEG_* definitions.
+ * against the PHYLINK_PCS_NEG_* definitions.
  */
 void pcs_link_up(struct phylink_pcs *pcs, unsigned int neg_mode,
 		 phy_interface_t interface, int speed, int duplex);