cxp upconn: rename high speed upconn to bitrate2x

src/gateware/cxp_upconn.py

@@ -11,7 +11,7 @@ class CXP_UpConn(Module, AutoCSR):
         self.clock_domains.cd_cxp_upconn = ClockDomain()
         self.clk_reset = CSRStorage(reset=1)
 
-        self.high_speed_upconn = CSRStorage()
+        self.bitrate2x_enable = CSRStorage()
 
         # # #
 
@@ -42,7 +42,7 @@ class CXP_UpConn(Module, AutoCSR):
             Instance("BUFGMUX",
                 i_I0=pll_cxpclk,
                 i_I1=pll_cxpclk2x,
-                i_S=self.high_speed_upconn.storage,
+                i_S=self.bitrate2x_enable.storage,
                 o_O=self.cd_cxp_upconn.clk
             ),
             AsyncResetSynchronizer(self.cd_cxp_upconn, ~pll_locked | self.clk_reset.storage)