lib: make strmhz available in SPL

When setting up a DDR controller it is useful to be able to display
frequencies in a readable form. Make the strmhz() function available in
SPL builds provided there is full vsprintf available.

Reviewed-by: Tony O'Brien <tony.obrien@alliedtelesis.co.nz>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Chris Packham <judge.packham@gmail.com>
1 file changed