Apply CLOCK_BUFFER_TYPE on an input clock to describe
what type of clock buffer to use.
By default, Vivado synthesis uses
BUFGs for clock buffers. Supported values are BUFG,
BUFH, BUFIO, BUFMR, BUFR or none. The CLOCK_BUFFER_TYPE attribute can be placed on any top-level clock port.
CLOCK_BUFFER_TYPE works in RTL and XDC.