ptp: fix typo of "mechanism" in Kconfig help text

Fix typo s/mechansim/mechanism/
Signed-off-by: NAntonio Borneo <antonio.borneo@st.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/ptp/Kconfig

@@ -97,8 +97,8 @@ config PTP_1588_CLOCK_PCH
 	help
 	  This driver adds support for using the PCH EG20T as a PTP
 	  clock. The hardware supports time stamping of PTP packets
-	  when using the end-to-end delay (E2E) mechansim. The peer
-	  delay mechansim (P2P) is not supported.
+	  when using the end-to-end delay (E2E) mechanism. The peer
+	  delay mechanism (P2P) is not supported.
 
 	  This clock is only useful if your PTP programs are getting
 	  hardware time stamps on the PTP Ethernet packets using the