move 1st-stage i2c metastability synchronizer into 12 MHz domain

this should greatly increase the amount of time allowed for
the signal to settle down and hopefully reduce chatter/bounce.

betrusted_soc.py

@@ -1566,7 +1566,7 @@ def __init__(self, platform, revision, sys_clk_freq=int(100e6), legacy_spi=False
 
         # I2C interface ----------------------------------------------------------------------------
         self.submodules.i2c = ClockDomainsRenamer({"sys":"sys_always_on"})(i2c.RTLI2C(platform, platform.request("i2c", 0)))
-        self.comb += self.i2c.filter_clk.eq(self.crg.cd_clk50_always_on.clk) # slower clock for de-metastabilizing the slow/jitter edges of I2C
+        self.comb += self.i2c.filter_clk.eq(self.crg.cd_usb_12.clk) # slower clock for de-metastabilizing the slow/jitter edges of I2C
         self.add_csr("i2c", use_loc_if_exists=True)
         self.add_interrupt("i2c", use_loc_if_exists=True)