docs: networking: phy: add missing space

Missing space between "pins'" and "strength"

Signed-off-by: Casper Andersson <casper.casan@gmail.com>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Link: https://lore.kernel.org/r/20221004073242.304425-1-casper.casan@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: cappe987

Documentation/networking/phy.rst

@@ -120,7 +120,7 @@ required delays, as defined per the RGMII standard, several options may be
 available:
 
 * Some SoCs may offer a pin pad/mux/controller capable of configuring a given
-  set of pins'strength, delays, and voltage; and it may be a suitable
+  set of pins' strength, delays, and voltage; and it may be a suitable
   option to insert the expected 2ns RGMII delay.
 
 * Modifying the PCB design to include a fixed delay (e.g: using a specifically