Remove default constructor from i2c also

include/utl/com/i2c_bb.h

@@ -65,7 +65,7 @@ namespace utl {
       //! \brief A default destructor, allow destructor from derived only
       ~i2c_bb_i () noexcept = default;
       //! \brief A default constructor
-      i2c_bb_i (uint32_t clk =100000) noexcept
+      i2c_bb_i (uint32_t clk) noexcept
             : usec_ {1000000/(2*clk)} { }
    //!@}
 
@@ -247,7 +247,7 @@ namespace utl {
    //!@{
    protected:
       //! \brief Constructor
-      i2c_bb_i (uint32_t clk =100000) noexcept
+      i2c_bb_i (uint32_t clk) noexcept
             : usec_ {1000000/(2*clk)} { }
       //! \brief Virtual destructor
       virtual ~i2c_bb_i () noexcept  = default;