soc/sifive/fu540: Add helper function to get tlclk frequency

tlclk is not specific to the UART block in the FU540, so let's calculate
its frequency in clock.c.

Change-Id: I270920027f1132253e413a1bf9feb4fe279b651a
Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Reviewed-on: https://review.coreboot.org/c/29335
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Philipp Hug <philipp@hug.cx>

0 files changed, 0 insertions, 0 deletions